The Court : A. INTRODUCTION 1. In the court below, the Magistrate convicted the 1st respondent of Charge (2) – taking part in an unlawful assembly; the 2nd respondent of Charge (3) – inciting others to take part in an unlawful assembly; and the 3rd respondent of Charge (4) – taking part in an unlawful assembly; and sentenced the 1st respondent to a community service order of 80 hours; the 2nd respondent to a community service order of 120 hours and the 3rd respondent to 3 weeks’ imprisonment suspended for 1 year. 2. By a judgment handed down on 17 August 2017 (“Judgment”), we allowed the Secretary for Justice’s application for review against sentence brought under section 81A of the Criminal Procedure Ordinance (“CPO”).[1] We held that the original sentences imposed by the Magistrate on the respondents were wrong in principle and were manifestly inadequate. We accordingly set them aside and substituted : (1) 6 months’ imprisonment for the 1st respondent in respect of Charge (2); (2) 8 months’ imprisonment for the 2nd respondent in respect of Charge (3); and (3) 7 months’ imprisonment for the 3rd respondent in respect of Charge (4). 3. The respondents now seek leave to appeal to the Court of Final Appeal. Under section 32(2) of the Hong Kong Court of Final Appeal Ordinance,[2] leave to appeal shall not be granted unless (1) it is certified by the court below that a point of law of great and general importance was involved in the decision or (2) it is shown that substantial and grave injustice has been done. All the 3 respondents have already directly applied to the Court of Final Appeal under the second limb.[3] Invoking also the first limb, the 2nd and 3rd respondents by their respective notice of motion dated 4 and 27 September 2017 applied to this Court for a certificate that the points of law of great and general importance as set out therein were involved in the Judgment. 4. By the parties’ consent, the applications by the 2nd and 3rd respondents are to be disposed of on paper without an oral hearing. We have duly considered the parties’ written submissions and all the authorities that they seek to rely on. We now hand down our judgment. 5. For the reasons to be articulated below, we dismiss both applications. The reasons may be summarized as follows. 6. As will be seen shortly, it is well established by both Hong Kong and English appellate authorities that : (1) On an application for review of sentence, the Secretary for Justice is not entitled to change the factual basis for sentence that it had relied on at trial and ask the Court of Appeal to inquire into facts which had not been pursued below. Even if the sentencing court had proceeded on a wrong factual basis for sentence, it is not open to the Secretary for Justice to make such an assertion before the Court of Appeal if the prosecution had the opportunity to have it corrected at trial but they had not sought to do so. The Court of Appeal will adopt the same factual basis as it was before the sentencing court. (2) Subject to (1), where the ground for review is that the sentencing court acted on an erroneous factual basis, the Court of Appeal is entitled to examine the evidence adduced below to consider if, based on the facts proved, admitted or not in dispute, the sentencing court did make the error as asserted by the Secretary for Justice. If so, the Court of Appeal is entitled to correct the factual error and to consider if, based on the factual basis as corrected, the sentence imposed is wrong in principle or manifestly inadequate. If so, the Court of Appeal is entitled to interfere. 7. As a corollary of the proposition in [6(2)] above and according to first principle, where it is shown that, based on the facts proved, admitted or not in dispute, the sentencing court has failed to take into account certain matters which are relevant to sentence, the sentencing court has proceeded on an incomplete factual basis, rendering the sentence imposed wrong as a matter of law and principle. In such circumstances, the Court of Appeal is not bound by the findings made by the sentencing court for the purpose of sentence because those findings are incomplete for such purpose. The Court of Appeal is entitled to consider all the relevant matters including those wrongly ignored by the sentencing court to determine if in the overall circumstances of the case, the sentence imposed is wrong in principle and/or manifestly inadequate. If so, the Court of Appeal is entitled to interfere. 8. Applying the above principles, we held in the Judgment that according to the facts proved, admitted or not in dispute based on the evidence adduced before the Magistrate : (1) the unlawful assembly was a serious and large-scale unlawful assembly, involving violence; (2) the Magistrate had failed to take into account those relevant factors as identified by the Court; (3) the Magistrate had made the errors as identified by the Court; and (4) the sentences imposed by the Magistrate were wrong in principle and were manifestly inadequate. We then set aside the sentences imposed by the Magistrate and substituted them with immediate custodial sentences as stated. Neither the 2nd nor the 3rd respondent has been able to demonstrate an arguable case that we had erred in allowing the application for review as we did in the manner as described above. 9. Since the answers to the questions sought to be certified by the 2nd and 3rd respondents are well settled, and they have failed to show an arguable case that we had erred, we dismiss their applications. B. THE POINTS OF LAW SOUGHT TO BE CERTIFIED 10. By his notice of motion filed on 4 September 2017, the 2nd respondent applied for a certificate that the following points of law of great and general importance are involved in the Judgment (“R2’s Question”) : “ (1) Whether on an application by the Secretary for Justice for review of sentence pursuant to section 81A of the CPO, the Court of Appeal has the power to make any factual findings not made at the trial or contrary to findings made by the trial judge, where by reason of or in consideration of the same the sentence is increased? (“R2’s Sub-Question 1”) (2) If the Court of Appeal has such power, under what circumstances and to what extent should the Court of Appeal exercise such power?” 11. By his notice of motion filed on 27 September 2017, the 3rd respondent applied for a certificate that the following point of law of great and general importance is involved in the Judgment (“R3’s Question”) : “ In a Secretary for Justice’s sentence review application under section 81A of the CPO, is it correct that the Court of Appeal does not have the power to make any factual findings adverse to the defendants different from or in addition to those made by the tribunal of fact at trial?” C. THE BASIS FOR ALLOWING THE APPLICATION FOR REVIEW 12. To put the parties’ submissions and our discussion in context, it is necessary to briefly recap the basis of our judgment in allowing the Secretary’s application for review against sentence. 13. In Part B of the Judgment, we noted that the defence did not dispute the background of the incident, or the acts of the respondents as recorded in the video clips which were produced by way of admitted facts; and that they did not seriously dispute the evidence of various prosecution witnesses.[4] We then summarized the prosecution case based on the evidence, which was either admitted or not in dispute. 14. After summarizing the respondents’ evidence (Part C) and referring to the reasons for verdict (Part D), the reasons for sentence (Part E) and the parties’ submissions (Parts F and G), we in Part H set out the legal propositions and sentencing principles applicable to unlawful assembly involving violence. We subsequently summarized those propositions and principles in Secretary for Justice v Leung Hiu Yeung and Others, CAAR 3 of 2016, unreported, 11 September 2017 at [87] – [108]. We shall not repeat them here. 15. In Part I, we explained why, based on the evidence, the facts of the present case were serious and why it was a large-scale unlawful assembly involving violence by reference to the matters discussed at [157] – [164]. We went on to observe at [165] that according to the respondents’ conduct after the incident they had shown no genuine remorse for the offences they had committed. We concluded at [166] that given the seriousness of the offences, it was necessary for the court to place more weight on punishment and deterrence and correspondingly less weight on the respondents’ personal circumstances, motives and rehabilitation. The appropriate sentence must be sufficiently deterrent to prevent them from re-offending and to warn others not to follow suit. The appropriate sentence must be one of immediate custodial sentence.[5] 16. For the errors that the Magistrate made as listed out at [167(1) – (5)], we at [168] held that it was wrong in principle for her to sentence the respondents to community service orders or suspended sentence, as the case may be, and that the sentences she passed were manifestly inadequate. 17. We at [169] stated the correct starting points for sentence to be : (1) 8 months for the 1st respondent in respect of Charge (2); (2) 10 months for the 2nd respondent in respect of Charge (3); and (3) 8 months for the 3rd respondent in respect of Charge (4). We then exercised our discretion in accordance with customary practice to reduce the sentence by one month for all the respondents on account of the fact that it was the Secretary’s application for review. In respect of the 1st and 2nd respondents, since they had already completed their community service orders, we further reduced their sentence by one month. That further reduction was made because of the principle of double jeopardy : see Attorney General’s Reference Nos 4 and 7 of 2002 [2002] 2 Cr App R (S) 77, per Lord Woolf LCJ at [34]. We finally imposed on the respondents the sentences as stated at [2] above. 18. To conclude, we reiterated at [171] of the Judgment that the respondents were not convicted of and sentenced for the offences for exercising their rights to assembly, demonstration and expression, which rights the law fully recognizes and protects. They were so convicted and sentenced simply because they had trespassed the boundaries laid down by the law for peaceful assembly by conducting themselves in the seriously unlawful manner as established by the evidence. D. THE PARTIES’ SUBMISSIONS D1. The 2nd respondent’s submissions 19. Mr Robert Pang SC (leading Mr Michael Chai and Ms Priscilla Chow), for the 2nd respondent, submitted that in reaching the conclusion as we did and holding that the Magistrate overlooked certain facts, we effectively increased the sentence of the 2nd respondent on facts which were not made at the trial or contrary to the findings made by the Magistrate. Counsel submitted that whether the Court of Appeal is entitled to do so, thus R2’s Question, is a question of law involving great and general public importance. The great and general public importance of R2’s Question is self-evident. Mr Pang went on to submit that the Court of Appeal is not entitled to do so and R2’s Sub-Question 1 must be answered in the negative. 20. Mr Pang relied on what he considered to be the practice of the English Court of Appeal by citing Archbold on Criminal Pleading, Evidence and Practice 2017, §7-445 and Taylor on Criminal Appeals (2nd Edn), §13.47. (1) The relevant passage in Archbold states that : “ The Court of Appeal will consider a reference on the basis of the facts proved or admitted; it would not constitute itself as a court of first instance inquiring into the facts which had not been pursued or proved in the Crown Court: Att. Gen.’s Reference (No. 95 of 1998) (R. v. Highfield), The Times, April 21, 1999, CA.” (2) The relevant passage in Taylor states that : “ The Court must review any sentence referred to it on the basis of the facts as they were before the sentencing judge. It is not open to the Attorney-General to invite the Court to sentence on a different factual basis, even where the sentencing judge has proceeded on a wrong basis if the prosecution could have but failed to correct it at the time. Nor is it the function of the Court to substitute their own view of the facts in light of new material.” Mr Pang submitted that the same practice is adopted in Hong Kong by relying on Attorney General v Li Ah-sang [1995] 2 HKCLR 239. 21. Mr Pang fairly recognized that in the recent judgment of Leung Hiu Yeung, supra, we at Part H2 set out the general principles concerning the factual basis of a review application before the Court of Appeal. However, he submitted that since R2’s Question has not been considered by the Court of Final Appeal, a certificate that a point of law of great and general importance should be granted. D2. The 3rd respondents’ submissions 22. The thrust of the submissions of Mr Edwin Choy (together with Mr Joe Chan), for the 3rd respondent, is similar to Mr Pang’s. He submitted that when reviewing a sentence, the Court of Appeal must not act as a fact-finding body and make any factual findings adverse to the defendants different from or in addition to those made by the sentencing court at trial. 23. Mr Choy cited R v Sin Yau Ming [1992] 1 HKCLR 127; Raymond Chen v HKSAR (2010) 13 HKCFAR 728; Chou Shih Bin v HKSAR (2005) 8 HKCFAR 70; and 香港特別行政區　訴　張育強, HCMA 540/2011, unreported, 6 October 2011 to support the general proposition that in criminal appeals, an appellate court will be extremely slow to interfere with the findings made by the trial court. 24. As to the practice of the Court of Appeal in dealing with an application for review against sentence, Mr Choy similarly relied on Li Ah-Sang, supra and R v Highfield, supra where Judge LJ observed that : “ Whether a sentence referred to the Court of Appeal by the Attorney General was unduly lenient was a question which had to be decided not in the light of what was alleged but of what was proved or found to have been established. The Court of Appeal could not constitute itself as a court of first instance inquiring into facts which had not been pursued or proved in the Crown Court.” D3. The Secretary’s submissions 25. Mr David Leung, SC, DDPP (leading Ms Annie Li, PP), for the Secretary, took two main points : (1) In allowing the Secretary’s application for review, we had not admitted any fresh evidence. We only examined the evidence which was proved or admitted at trial to determine if the Magistrate, when passing sentences on the respondents, had erroneously considered or overlooked such evidence. Thus both R2’s Question and R3’s Question were simply not involved in the Judgment. (2) What the 2nd and 3rd respondents seek to certify are not points of law, let alone points of great and general public importance. 26. In elaborating on point (1), Mr Leung submitted that if the ground for review is that the sentencing court made an erroneous factual finding or ignored certain findings of fact in sentencing, the Court of Appeal certainly has the power to determine the proper factual basis from the evidence proved or admitted below in order to consider the proper sentence that should have been imposed. Were it otherwise, an absurdity would arise in that even when it is demonstrated that the original sentence was imposed on a wholly erroneous basis, the mistake in sentencing could never be rectified by the Court of Appeal on the review application. In support, Mr Leung cited Attorney General’s Reference Nos 4 and 7 of 2002, supra; Attorney General’s Reference Nos, 90 and 91 of 2003 [2004] EWCA Crim 1839; Secretary for Justice v Au Chi Hang & Others [2006] 2 HKLRD 310; and Leung Hiu Yeung, supra. 27. Mr Leung distinguished Li Ah-sang and R v Highfield by submitting that because of the prosecution’s particular conduct before the sentencing court in those cases, the Attorney General was not allowed to seek a review on the basis which was different or which had not been pursued or proved below. Mr Leung next submitted that the proposition mentioned in the passages in Archbold and Taylor only applies to cases where the prosecution had the opportunity to have the mistake corrected at trial but they had not sought to do so. By drawing these distinctions, Mr Leung submitted that the present case is different as in the Judgment, we had not changed the factual basis identified and established by the prosecution at trial. 28. Concerning point (2), Mr Leung submitted that by reason of his submissions in respect of point (1), we in the Judgment did not assume the role of a trial court to carry out a fact-finding exercise on our own. All we did was, on the basis of the evidence adduced below which was proved or admitted or was not in dispute, to give those facts and evidence the proper weight in order to consider if the sentences imposed by the Magistrate were wrong in principle and/or manifestly inadequate and if so, the proper sentences. Thus R2’s Question and R3’s Question are not points of law, let alone points of law of great and general importance. E. DISCUSSION 29. In reviewing a sentence under section 81A of the CPO, the Court of Appeal must act on a proper factual basis to determine if it is wrong in principle and/or manifestly inadequate. For passing a sentence and reviewing the correctness of the sentence passed is always a fact-sensitive exercise. E1. The general principles 30. Recently in Leung Hiu Yeung, supra, we had had the opportunity of considering the general principles on how the Court of Appeal would approach the factual basis for the purpose of reviewing a sentence. We stated :[6] “ 124. The respondents submitted that in dealing with an application for review of sentence, the Court of Appeal must take the factual findings made by the trial magistrate as the only basis. The Court of Appeal cannot act beyond his factual findings. They cited Attorney General v Li Ah-sang [1995] 2 HKCLR 239 in support. In our view, the respondents’ submissions are questionable. And if one reads Li Ah-sang carefully, one can readily see that it does not support their contention. 125. The general principle is that in dealing with an application for review of sentence, the Court of Appeal will proceed on the basis of the facts proved or admitted; it would not constitute itself as a court of first instance inquiring into facts which had not been pursued or proved in the court below. See Archbold on Criminal Pleading, Evidence and Practice 2017, §7-445. Accordingly, the Court of Appeal will generally proceed on the basis of the facts as found by the court below. However, it does not necessarily follow that in every scenario, the Court of Appeal is, in terms of facts, bound by the lower court’s factual findings. (1) Pursuant to section 81B(3) and section 83V of the Criminal Procedure Ordinance, the Court of Appeal may, if it thinks it necessary or expedient in the interests of justice, admit fresh evidence. Although the Court of Appeal will be slow to admit fresh evidence and section 83V(5) also provides that in no case shall any sentence be increased by reason of or in consideration of any evidence which was not given at the trial, it does not detract from the power of the Court of Appeal to admit fresh evidence in an application for review. (We have not exercised this power in the present case : see [128] below.) (2) If the ground for review is that the lower court had made an erroneous factual finding, the Court of Appeal may examine if the finding in question is correct. Secretary for Justice v Au Chi Hang & Others [2006] 2 HKLRD 310 is an example. There, the first instance judge found that the weapons concerned were not offensive weapons as mentioned in the relevant authority. In applying to review the sentence, the Secretary for Justice submitted that the judge erred in making such a finding and had thereby failed to apply the relevant authority in sentencing. The Court of Appeal rejected the Secretary for Justice’s submission. The Court further pointed out the wooden pole and iron pole in question had not been seized as exhibit. Their dimensions were only described in the Admitted Facts ([33]). That being the case, the Court of Appeal said that as the Court did not have the advantage of the judge having the “feel” of the case, it was unable to overturn the judge’s finding that the weapons were not offensive weapons ([39]). As Au Chi Hang demonstrates, if it is the ground for review, the Court of Appeal may examine the factual findings made by the lower court although the Court of Appeal will be slow to interfere. (3) If based on evidence which had been proved or admitted or which had been adduced and was not in dispute, certain facts which are plainly relevant to sentence, whether they are in favour of the defendant or not, have been overlooked by the lower court, the sentence imposed by the lower court is erroneous as a matter of law and principle. In such circumstances, the Court of Appeal is not bound by the factual findings of the lower court because such findings are incomplete, having failed to take into account relevant facts. When the Court of Appeal considers those facts which ought to be considered, it does not depart from the general principle that in an application for review against sentence, the Court of Appeal will proceed on the basis of facts proved or admitted and will not inquire into facts not pursued or proved as if it were a first instance court. For the Court of Appeal only considers those evidence proved, admitted or not in dispute which are relevant to sentence but have been wrongly ignored by the first instance court. 126. The facts in Li Ah-sang are special. (1) There (the 2nd Case), the defendant admitted two charges of employing persons not lawfully employable. The magistrate fined him HK$5,000.00 on each charge. The Attorney General applied for a review on the ground that the employees employed by the defendant were illegal immigrants. The sentence was hence wrong in principle and manifestly inadequate. However, before sentencing the defendant, the same magistrate at the trial concerning the employees (the 1st Case) found that they were not illegal immigrants. Thus when the magistrate sentenced the defendant, he proceeded on the basis that the employees were not illegal immigrants. The prosecution there and then did not raise any objection and in fact did not allege that the employees were illegal immigrants. (2) The Attorney General submitted that since whether the employees were illegal immigrants was a live issue as a matter of law, the Court of Appeal might rule on it. The Court of Appeal however disagreed. It took the view that as the magistrate did not make any ruling on this point in the 2nd Case, there was no legal question arising for the Court of Appeal to consider. (3) The Court of Appeal went on to say that the magistrate in sentencing the defendant assumed that the employees were not illegal immigrants on the basis of his finding in the 1st Case. The prosecution did not raise any objection or ask to hold a Newton hearing to determine their status. In such circumstances, it is not open to the Attorney General to seek a review other than the facts on which the magistrate chose to find. The Court of Appeal would therefore adopt the same factual basis for the review. 127. Properly understood, the way which the Court of Appeal in Li Ah-sang dealt with the factual basis for review is consistent with the general principle stated in [125] above. As the Court of Appeal would proceed on the basis of the facts proved or admitted, it would not constitute itself as a court of first instance inquiring into facts which had not been pursued or proved in the court below, the Court of Appeal therefore rejected the Attorney General’s submission and held that it would adopt what the magistrate had accepted and not disputed by the prosecution as the factual basis for review. That is to say, the employees employed by the defendant were not illegal immigrants. Li Ah-sang did not establish the proposition advocated by the respondents, namely, in dealing with an application for review against sentence, the Court of Appeal must take the factual findings made by the trial magistrate as the only basis and the Court of Appeal cannot act beyond his factual findings.” 31. We take this opportunity to further elaborate on the above propositions with the benefit of the additional authorities cited to us by the parties. E1.1 The proposition in [125(2)] 32. In Leung Hiu Yeung, we cited Au Chi Hang, supra, as an example for the proposition stated in [125(2)] above that if the ground of review is that the lower court had made an erroneous factual finding, the Court of Appeal is entitled to consider if the finding is correctly made. There are other local and English authorities illustrating the same point. 33. In the local case of Lau Chiu-tak, supra, there were two applications for review before the Court of Appeal. In the first case, the respondent was charged with wounding under section 19 of the Offence Against the Person Ordinance[7] and was sentenced to a suspended prison sentence and ordered to pay compensation to the victim. In the second case, the respondent was charged with possession of tetrahydrocannabinol for trafficking. On the assumption that the drug was cannabis, the district judge sentenced him to 12 months’ imprisonment. The Attorney General sought a review of sentence (1) in the first case on the grounds that the sentence was wrong in principle and manifestly inadequate; and (2) in the second case on the ground that the sentence was manifestly inadequate. 34. Delivery the Judgment of the Court of Appeal, Sir Alan Huggins VP stated the general principles at p 26D – F : “ It is enough to say that where the application is based upon an error of principle it is incumbent on the Attorney General to identify the nature of the error alleged, and it goes without saying that he is entitled to cite authority to establish the error. Where it is alleged that a sentence is manifestly inadequate or manifestly excessive, he must clearly be allowed to say which, although it would be strange if that matter were in doubt. He may properly draw attention to any matter appearing on the record, but may not adduce new evidence (for example as to the incidence of a particular crime) with a view to an increase of sentence : s.83V(5).[8] Previously decided cases may be cited for the purpose of showing that the sentence under review is substantially and unjustifiably out of line with the usual tariff for that kind of offence.” 35. In allowing the applications for review, Huggins VP held that in the first case the judge erred in suggesting that, because the respondent was not violent in nature and acted on the spur of the moment, he did not intend the wound he in fact caused and that he might not have intended to cause such a serious wound, but he did intend to cause the wound (p 26H). In effect, Huggins VP held that the judge erred on the finding concerning the respondent’s intention. 36. In the second case, the judge sentenced the respondent on the erroneous assumption that the drug was cannabis when in fact it was something else. Huggins VP held that the sentence was manifestly inadequate and substituted a sentence of 2½ years’ imprisonment on the correct factual basis that the drug was tetrahydrocannabinol (p 27 C- D). 37. In the English case of Attorney General’s Reference Nos 90 and 91 of 2003, supra, the defendant was sentenced to 5 years’ imprisonment for possession of a controlled drug of class A (ecstasy) with intent. Initially the defendant pleaded not guilty. Later, he indicated his wish to plead guilty but only on the basis that he believed the drug to be amphetamine but not ecstasy. The prosecution did not accept this basis of plea. In the end, the defendant did not pursue his basis of plea and no Newton hearing was held on his alleged belief. The defence did not mention his alleged belief in mitigation. However, in the reasons for sentence, the judge sentenced the defendant on the basis that he believed that the drug was amphetamine. On review of sentence, the defendant submitted that the Court of Appeal should not go behind the conclusion of the judge that he should be sentenced on the basis that he believed the drug to be amphetamine. R v Highfield was cited in support. 38. In rejecting the submission, Latham LJ said : “ Further, it seems to us, having regard to the history of the matter, that we can and should take the view that the judge fell into error in sentencing the offender McFadden on the basis that he did, namely believing the tablets to be amphetamine. The history of the proceedings that we have related makes it quite plain that although that was a matter which was put forward by the offender when he first changed his plea, it was not pursued by him at the date when the judge sentenced him and was no part of his mitigation. In those circumstances it is abundantly clear that the judge simply made a mistake as to the basis upon which he fell to be sentenced. That is quite a different situation from the envisaged and dealt with in the case of R v Highfield. We do not consider that we are precluded from dealing with this offender on the basis upon which he should have been dealt with, namely that he did not have that basis of plea as any mitigation of his sentence.” We will return to R v Highfield shortly. 39. In another English case of Attorney General’s Reference Nos 4 and 7 of 2002, supra, the English Court of Appeal considered that the sentence under review was unduly lenient. Woolf LCJ said : “ 33. A question arose during argument as to whether it was inappropriate in this situation to take into account the fact that the judge who was responsible for sentencing was not aware of the extent to which the offences were committed on bail. This was a case where the sentence, even without that factor, was undoubtedly unduly lenient. Mr Pownall, on behalf of the Attorney General, said that in order to achieve fairness we should not look at matters of which the judge who passed the unduly lenient sentence was not aware. We disagree. We consider that it would be unfortunate, once we decided to intervene, if we were to deal with an offender on other than the actual facts. That is what we propose to do.” In other words, Woolf LCJ held that once the Court of Appeal concluded that the sentence under review was manifestly inadequate, it was entitled to pass sentence on the actual facts, although those facts were not before the sentencing court. E1.2 The proposition in [125(3)] 40. The proposition in [125(3)] is a corollary of the proposition in [125(2)]. Further, according to first principle, a sentencing court must take into account all relevant circumstances before passing the sentence. If the sentencing court overlooks certain relevant matters which had been proved, admitted or which had been adduced and not in dispute, the sentence passed is liable to be reviewed because of the failure to take into account all the relevant circumstances rendering it wrong as a matter of law and principle. We have also explained why in considering those facts which the sentencing court had wrongly ignored, the Court of Appeal is still acting within the permissible bounds. E2. The authorities relied on by the respondents 41. The 2nd and 3rd respondents principally rely on Li Ah-sang, R v Highfield, and the passages in Archbold and Taylor. Properly understood, they do not detract from the general propositions we have stated. 42. The point that Mr Pang and Mr Choy seek to derive from Li Ah-sang is effectively the same as advocated by the respondents in Leung Hiu Yeung, namely, that in reviewing a sentence, the Court of Appeal is always bound by the factual findings made by the sentencing court. For the same reasons that we have stated in Leung Hiu Yeung, at [126] and [127], this proposition is based on a misunderstanding of effect of Li Ah-sang. It is erroneous and does not accurately represent the approach that the Court of Appeal would adopt in dealing with the factual basis for reviewing a sentence. It must be rejected. 43. In R v Highfield, supra, the defendant was charged with an offence of causing death by dangerous driving. After trial had commenced, she pleaded guilty and was sentenced to a community service order of 240 hours and disqualified from driving for 5 years. At the trial, when the prosecution opened the case, nothing was said about either alcohol or prolonged bad driving. Rather, counsel said there was no information to show why the defendant drove onto the wrong side as she did. The judge concluded that there was an isolated or momentary error with the most tragic consequences and he identified as the main aggravating feature that the defendant did not stop and help after the accident. The Attorney General applied for a review of sentence on the ground that the sentence was manifestly inadequate and highlighted the aggravating features of drinking alcohol before driving and the defendant having driven badly for a significant distance. In rejecting the application, Judge LJ observed that it could not constitute itself as a court of first instance inquiring into facts which had not been pursued or proved in the Crown Court. 44. Judge LJ’s observation was later explained by the English Court of Appeal in Attorney General’s References Nos 114-116 of 2002 and Nos 144-5 of 2002 [2003] EWCA Crim 3374. There, the sentencing judge erred as a matter of law in making no confiscating order on the purported ground of want of jurisdiction. Had he not erred, he would have to hear evidence to decide if a confiscation order should be made. On review, the offender argued that it is the normal practice that all factual matters necessary for the purpose of deciding an Attorney General’s reference are set out in the application for leave and the Court of Appeal had normally refused to entertain any issue of fact on the hearing of a reference. R v Highfield and Judge LJ’s observation was cited. Rose VP at [28] said : “ …What Judge LJ was correctly observing was that the Attorney General could not seek to re-open the way in which the case had been put by the Crown in the court below to require this court to enquire into facts which, whatever the explanation for the decision made by the Crown at that stage, had not been pursued. In this case, the facts giving rise to the reference are not in dispute: the Crown has always wanted to pursue confiscation and has only been deprived of the opportunity of so doing by an error of law in the sentencing process.” 45. Thus understood, what the English Court of Appeal had decided in R v Highfield is effectively the same as what our Court of Appeal did in Li Ah-sang as we have explained in Leung Hiu Yeung, supra, at [126]. That is to say, when in the proceedings below, the prosecution chose to adopt a particular stance which was accepted by the sentencing court as the factual basis for sentencing, the Court of Appeal will not allow the prosecution, in an application to review the sentence, to pursue a different factual basis not pursued below. It is so even if the stance adopted by the court below was erroneous when the prosecution had the opportunity to have it corrected but had not done so. In such circumstances, the Court of Appeal will not permit the prosecution to re-open the matter and will simply proceed on the same factual basis as adopted by the sentencing court. 46. As noted at [20(1)] above, Archbold, §7-445 cited R v Highfield in support. When R v Highfield is properly understood (as explained above), it does not lend any further support to the respondents. 47. The passage in Taylor, §13.47 consists of two statements : (1) “The Court must review any sentence referred to it on the basis of the facts as they were before the sentencing judge. It is not open to the Attorney-General to invite the Court to sentence on a different factual basis, even where the sentencing judge has proceeded on a wrong basis if the prosecution could have but failed to correct it at the time.” (2) “Nor is it the function of the Court to substitute their own view of the facts in light of new material.” (1) In its proper context, the first sentence and the second sentence in the first statement should be read together. So read, the effect of the first statement is no different from R v Highfield properly understood. Even if the first sentence in the first statement is to be read independently, it must be qualified by the English cases discussed above. It cannot be cited as a free-standing proposition that in every scenario, the Court of Appeal must review any sentence referred to it on the basis of the facts as they were before the sentencing judge. (2) The second statement is irrelevant for present purpose as we have not adduced any new evidence or considered any new material. 48. Finally, the authorities cited by Mr Choy on the general position that an appellate court would adopt on findings of facts by the lower courts are decisions made in different contexts other than a review of sentence ([23] above). They do not address the question of how the Court of Appeal would approach the factual basis for reviewing a sentence. E3. Summary of the applicable propositions 49. To summarize, in our view, the authorities discussed above firmly establish the following propositions : (1) On an application for review of sentence, the Secretary for Justice is not entitled to change the factual basis for sentence that it had relied on at trial and ask the Court of Appeal to inquire into facts which had not been pursued below. Even if the sentencing court had proceeded on a wrong factual basis for sentence, it is not open to the Secretary for Justice to make such an assertion before the Court of Appeal if the prosecution had the opportunity to have it corrected at trial but they had not sought to do so. The Court of Appeal will adopt the same factual basis as it was before the sentencing court. (2) Subject to (1), where the ground for review is that the sentencing court acted on an erroneous factual basis, the Court of Appeal is entitled to examine the evidence adduced below to consider if, based on the facts proved, admitted or not in dispute, the sentencing court did make the error as asserted by the Secretary for Justice. If so, the Court of Appeal is entitled to correct the factual error and to consider if, based on the factual basis as corrected, the sentence imposed is wrong in principle or manifestly inadequate. If so, the Court of Appeal is entitled to interfere. (3) As a corollary of the proposition in (2) and according to first principle, where it is shown that, based on the facts proved, admitted or not in dispute, the sentencing court has failed to take into account certain matters which are relevant to sentence, the sentencing court has proceeded on an incomplete factual basis, rendering the sentence imposed wrong as a matter of law and principle. In such circumstances, the Court of Appeal is not bound by the findings made by the sentencing court for the purpose of sentence because those findings are incomplete for such purpose. The Court of Appeal is entitled to consider all the relevant matters including those wrongly ignored by the sentencing court to determine if in the overall circumstances of the case, the sentence imposed is wrong in principle or manifestly inadequate. If so, the Court of Appeal is entitled to interfere. 50. We reject any submissions of Mr Pang and Mr Choy which are contrary to the above propositions. We would also add that if the Court of Appeal does not have the power to correct the factual basis for reviewing a sentence under propositions (2) and (3) above, the absurdity as identified by Mr Leung in his submission would arise (see [26] above). That simply cannot be right. E4. Had we made any impermissible findings of fact? 51. Mr Pang submitted, without explanation, that we had increased the sentence of the 2nd respondent on facts which were not made at the trial or contrary to the findings made by the Magistrate. Likewise, Mr Choy submitted that we had made findings adverse to the 3rd respondent different from or in addition to those made by the Magistrate without elaboration. 52. In Part I of the Judgment, we detailed the reasons why based on the evidence, admitted or not in dispute, the present offences were serious, why it was a large-scale unlawful assembly involving violence; why the Magistrate had erred in failing to have proper regard and/or give due weight to various factors relevant to sentence as identified by us; and why she had made the errors as discussed. For the reasons we articulated and based on the applicable principles, we held that we must interfere and, proceeding on the correct and complete factual basis, set aside the sentences imposed by the Magistrate and substituted them with immediate custodial sentences as stated. Neither Mr Pang nor Mr Choy has been able to show an arguable case that we have erred in how we dealt with the matter in such manner. F. CONCLUSION 53. For the above reasons, we consider that the answers to both R2’s Question and R3’s Question are well settled by authorities. They do not give rise to any question of law of great and general importance that warrants leave to be given to the 2nd and 3rd respondents to appeal to the Court of Final Appeal : see Chim Pui Chung v HKSAR [1999] 1 HKLRD 836. In any event, the 2nd and 3rd respondents have failed to demonstrate an arguable case that we had erred in the way as they had contended. 54. We accordingly refuse to certify R2’s Question and R3’s Question as one of great and general public importance. The notices of motion filed by the 2nd and 3rd respondents are all dismissed. Mr David Leung, SC, DDPP and Miss Annie Li, PP, of the Department of Justice, for the Applicant Mr Robert Pang, SC, Mr Michael Chai and Ms Priscilla Chow, instructed by M/s Ho, Tse, Wai & Partners, for the 2nd Respondent Mr Edwin Choy and Mr Joe Chan, instructed by M/s Ho, Tse, Wai & Partners, for the 3rd Respondent [1] Cap 221. [2] Cap 484. [3] The 1strespondent did so on 11 September 2017; the 2ndand 3rd respondents, 14 September 2017. [4] Save and except PW11, whose evidence the trial magistrate rejected. [5] As noted at [166], Mr Shek, counsel for the 1st respondent, confirmed that insofar as the 1strespondent was concerned, there was no need to consider other sentencing options under section 109A of the CPO should we decide to allow the application for review against sentence. [6] The quoted paragraphs are taken from the English translation of the Judgment. [7] Cap 212. [8] That is section 83V(5) of the CPO, which provides that in no case shall any sentence be increased by reason of or in consideration of any evidence which was not given at the trial.