Summarize the following court judgment. ivil Appeal No. 2977 of 1984. From the Judgment and Order dated 18.2.1982 of the Calcutta High Court in S.A.T. No. 87 of 1981. D.K. Sen	 Dr. Meera Agarwal and R.C. Mishra for the Appel . lants. A.K. Sen	 S.K. Banerjee and P.K. Mukerjee for the Re spondents. The Judgment of the Court was delivered by K.N. SAIKIA	 J. This defendants ' appeal by special leave is from the judgment and order of the High Court of Calcutta dated 18th February	 1982 in S.A.T. No. 87 of 1981 summarily dismissing the Second Appeal against the appellate order in T.A. No. 381 of 1980 which affirmed the judgment and decree in title suit No. 56 of 1966. The instant second respondent Narendra Nath Mukherjee leased out the land measuring 6 cottas 5 chittaks 30 sq. at 512/A Russa Road	 now known as 34/A Shyama Prasad Mukher jee Road	 Calcutta	 by a registered lease deed dated 26th September	 1946	 hereinafter referred to as 'the lease '	 at the first instance for a period of 10 years from 1st April	 1946 but if the lessee did not fail to pay the rent to the lessor and rates and taxes to the municipality during .that period	 the lease would be extended for a further period of 5 years i.e. upto 31st March	 1961 at the rent of Rs.250 in place of Rs.200 per month; and if he continued to do like wise	 it would be extended for a further period of 5 years	 that is	 upto 31st March	 1966	 at a monthly rent of Rs.300 in place of Rs.250; and if he continued to do likewise	 during the period of 20 years	 he would be entitled to obtain extension for a further maximum period of one year at a rent of Rs.500 per month in place of Rs.300 per month. 405 The instant appellants are stated to have exercised their option of extension at the expiry of 10 years for a period of 5 years i.e. from 1st April	 1956 to 31st March	 1961 on increased rental of Rs.250 per month and then for the second term of 5 years from 1st April	 1961 to 31st March	 1966 at the increased rental of Rs.300 per month. During the lease	 on 31st March	 1959 the instant second respondent by a registered instrument transferred the land to the first respondent who thereby became the landlord. Alleging that the instant appellants failed to exercise the option of extension for one year at an enhanced rent of Rs. 500 and also failed to give peaceful and vacant possession of the land to him	 the instant first respondent as plain tiff instituted title suit No. 56 of 1966 for ejectment khas	 possession and mesne profits. The instant appellants as defendants contested the suit by filing a joint written statement stating	 inter alia	 that they did not exercise option of renewal after the expiry of the original term of 10 years as they became thika tenants from 28th February	 1949 i.e. on the date of commencement of the Calcutta Thika Tenancy Act	 1949 as admitted by the plaintiff 's predecessor in interest	 the instant second respondent	 in Miscellaneous Execution case No. 126 of 1953 (Thika) before the Controller under the Calcutta Thika Tenancy Act	 1949	 hereinafter referred to as 'the Act '	 and by both the respondents in Misc. Judicial Case No. 74 of 1958 (Thika) before the said Controller. It was also stated that they (appellants) always paid rent at the rate of Rs.200 per month and never any enhanced rent; and that the first respondent 's claim for the differential rent was also rejected in the first respond ent 's suit No. T.S. 80 of 1965 and the appeal therefrom was also rejected and ultimately the special leave petition (Civil No. 1363/ 80) was also dismissed by the Supreme Court on 10th March	 1980. T.S. No. 56 of 1966 was decreed by the Trial Court wherefrom the appeal	 being T.A. No. 381 of 1980 was also dismissed. The Additional District Judge while dismissing T.A. 381/80 relied on the decision of the Calcutta High Court	 since reported in 	 holding that as the lease was for a period of 20 years and not for a period of 12 years sub section (5)(b) of Section 2 of the Act had no application; and that the respondents were not barred by waiver	 estoppel	 res judicata or principles analogous thereto because of the Misc. case No. 74 of 1958 filed by the second respondent under Section 5 of the Act as there could be no question of giving a status under the Act when in the facts of the case such a status was not available. The Second Appeal being S.A.T. 87 of 1981 having also been summarily dismissed by the High Court by the impugned order	 the appellants have preferred this Appeal by special leave. 406 Mr. D.K. Sen	 the learned counsel for the appellants submits	 inter alia	 that there could be no controversy about the appellants ' status of thika tenants in view of the fact that the lease was at the first instance for 10 years only and its first and subsequent extensions were contingent on the appellants ' regular payment of rents	 rates and taxes and enhancement of rent; that contingency did not happen as they did not pay any enhanced rent	 but simply were holding over; that the second respondent who is the predecessor in interest of the first respondent	 admitted the Thika Tenants status of the appellants in the earlier proceedings before the Controller and were therefore estopped from questioning that status; and that the learned Courts below erred in ignoring these vital pieces of evidence. Mr. Shankar Ghosh the learned counsel for the respond ents refuting submits that the lease having clearly been for a period of 20 years	 the appellants have rightly been held not to be thika tenants under the Act; and that there could be no estoppel against a statute. Two questions are	 therefore	 to be decided in this appeal	 namely	 whether the instant appellants acquired the status of thika tenants in respect of the lease; and whether there was estoppel	 waiver	 acquiesance or res judicata on the part of the respondents as in earlier proceedings they treated the appellants as thika tenants before the Control ler. The Act was passed in 1949 to make better provisions relating to the law of landlord and tenant in respect of thika tenancies in Calcutta. It came into force on the day on which the Calcutta Thika Tenancy Ordinance	 1948 ceased to operate. Section 2(5) in Chapter I defined "thika tenant" as follows: "(5) "thika tenant" means any person who holds	 whether under a written lease or other wise	 land under another person	 and is or but for a special contract would be liable to pay rent	 at a monthly or at any other periodical rate	 for that land to that another person and has erected or acquired by purchase or gift any structure on such land for a residential	 manufacturing or business purpose and includes the successors in interest of such person	 but does not include a person (a) who holds such land under that another person in perpetuity; or 407 (b) who holds such land under that another person under a registered lease	 in which the duration of the lease is expressly stated to be for a period of not less than twelve years; or (c) who holds such land under that another person and uses or occupies such land as a khattal." This new clause (5) was substituted by West Bengal Act 6 of 1953. The crucial words to be noted in clause (b) are that "the dura tion of the lease is expressly stated to be for a period of not less than twelve years. " In other words	 if the stated period is of less than 12 years the lessee will be a thika tenant and not otherwise. The important fea ture of the provision contained in section 5(1) of the Act is that the application for ejectment of the thika tenant has to be made to the Controller. We have	 therefore	 to ascertain the duration of the lease. Admittedly clauses 9	 11	 12 and 13 of the lease read as follows: "(9). If the second party lessee keeps the rent for two months in after at a time or if contravenes or commits any breach in respect of any provision of this deed or does not comply with his duties within 7 days in spite of service of warning notice or does not refrain from doing improper act	 or if he is declared insolvent then in spite of the tenure of this lease having not expired	 this lease	 that is the tenancy of the second party Lessee will be cancelled or extinguished and the first party Lessor will be entitled to take khas possession of the said property. No plea or objection of the second party Lessee will be entertained. The tenure of this lease will be for a period of ten years firstly from the 1st April	 1946 A.D. But if the second party Lessee	 performs acts regularly according to provisions within this stipulated period and pays fixed rent to the first party Lessor regularly and pays rates and taxes to the Municipality and does not default in doing his duties	 then the period will be extended under all the aforesaid terms for a further period of five years	 i.e. upto the 31st March	 196 1	 by fixing the monthly rent of Rs. 250 two hundred fifty rupees in place of Rs.200 two hundred rupees and the second party Lessee shall be bound absolutely by the aforesaid provisions in paragraphs 1 to 10 during the said enhanced period and all the said terms will remain in force	 408 only the rent of Rs.250 two hundred fifty in place of Rs.200 two hundred will be fixed. If the second party Lessee performs his acts regularly according to the aforesaid terms within last five years and is abide by the rules and pays the fixed monthly rent of Rs.250 two hundred fifty rupees to the first party Lessor month by month and pays the rates and tax to the Municipality then on the expiry of the said tenure of five years	 the tenure of this lease will be enhanced for a further period of five years	 i.e. upto 31st March	 1966 having fixed the monthly rent of Rs.300 three hundred rupees in place of Rs.250 two hundred fifty rupees under all the aforesaid terms in paragraphs 1 to 10 and the second party Lessee shall fully remain bound abso lutely by all the aforesaid terms and all the said rules shall fully remain in force	 only the monthly rent of Rs.300 three hundred in place of Rs.250 two hundred fifty will be fixed. If the lease is not determined for acting contrary to any provisions within the tenure of the aforesaid term	 then on the expiry of the said term as mentioned in this deed	 i.e. on the 1st April	 1966 A.D. the second party Lessee on paying the entire receivable amount in respect of the Demised premises to the first party Lessor	 will give khas possession of the said land by treating the houses etc. constructed on the Demised land	 i.e. the houses etc. constructed on the land by him	 i.e. the second party Lessee by treating the same to be a portion of the Demised land shall vacate the said houses and said land. But if the second party Lessee	 within the aforesaid 20 years	 performs acts according to all the aforesaid provisions duly and regularly and abide by all the same duly and regularly pays the fixed rent and rates and taxes at the proper place then the second party Lessee if so desire	 will be entitled to get the same for a further extended period of maximum one year from 1st April	 1966 A.D. by serving written Notice at least one month prior to the expiry of the aforesaid tenure of 20 years by fixing monthly rent of Rs.500 five hundred rupees in place of. Rs.300 three hundred under all the provisions of the aforesaid paragraph No. 1 to 10 and the first party Lessor shall be bound to grant the said extended period and if the second party Lessee	 accepts such extended period	 409 shall pay the entire dues of the first party Lessor within the last mentioned extended period upto the expiry of the said last ex tended period and upon that	 by demolishing the houses etc. constructed on the Demised land will remove and replace the same. The first party Lessor shall not have any objec tion to the same nor the same shall be tena ble and shall give khas possession on the Demised Land to the first party Lessor	 and in that event the first party Lessor shall be bound to give up his claim and contention on the houses etc. of the said second party Lessee and shall only take possession of the demised land that is	 in such circumstances the houses etc. constructed by the second party Lessee to be a portion of the demised land. But if for any reason the second party Lessee	 within the extended stipulated period does not give khas possession to the first party Lessor on the Demised land according to the aforesaid manner	 or if he neglects to do so or is unable then the first party Lessor shall not be bound to give up his claim in respect of the houses etc. constructed by the said second party Lessee. Moreover	 by treat ing the houses etc. constructed on the demised land to be a portion of the said land	 shall be entitled to take khas possession of the said Demised land and besides the same	 the first party Lessor shall also be entitled to get any other remedy or damage or compensation according to law." 'Ex praecedentibus et consequentibus optima fit inter pretatio. ' The best interpretation is made from the context. Every contract is to be construed with reference to its object and the whole of its terms. The whole context must be considered to ascertain the intention of the parties. It is an accepted principle of construction that the sense and meaning of the parties in any particular part of instrument may be collected 'ex antecedentibus et consequentibus; ' every part of it may be brought into action in order to collect from the whole one uniform and consistent sense	 if that is possible. As Lord Davey said in N.E. Railway vs Hastings	 (267)	 "The deed must be read as a whole in order to ascertain the true meaning of its several clauses	 and the words of each clause should be so inter preted as to bring them into harmony with the other provi sions of the deed if that interpretation does no violence to the meaning of which they are naturally susceptible." In construing a contract the Court must look at the words used in the contract unless they are such that one may suspect that they do not convey the intention correctly. If the words are clear	 there is 410 very little the Court can do about it. In the construction of a written instrument ' it is legitimate in order to ascer tain the true meaning of the words used and if that be doubtful it is legitimate to have regard to the circum stances surrounding their creation and the subject matter to which it was designed and intended they should apply. "The habendum in the lease states:. "Upon the prayer of the second party Lessee to take the said land in arrangement and settlement for a stipulated period for starting factories	 Lathe works	 manufacturing and repairing of Motor Car parts	 manufacturing and repairing Electric Fans and various manufacturing busi ness	 constructing pucca buildings on the said land or in portion thereof or subletting houses etc. and for constructing shop rooms etc. under the following terms and provisions	 to which he agreed and upon giving possession of the said land to the second party Lessee	 the second party Lessee hereby admit and promise that	 Particulars and four boundaries of the property in Schedule Ka are given as: In the District of 24 Parganas	 within the Police Station Bhowanipore	 in Mouza Bhowani pore Village	 within the jurisdiction of the Sub Registry Alipore	 in Government Khas Mahal	 in Division 6	 Sub Division "E" (E) relating to Dihi 55 gram	 in holding No. 224 within the surplus land of scheme No. 4 of the Calcutta Improvement Trust	 a portion of the plot No. 62 of the said scheme	 the rent free land measuring more or less 0 6 5 30 six kathas	 five chittaks	 thirty square feet together with foundation of the wall together with all fittings and fixtures and easement and other rights etc. with all rights and entire right is the property whose current Municipal premises No. 5/2A	 Russa Road and the second party Lessee have taken the said property on lease for a stipulated period of twenty years". (underlined by us) In clause 9 of the lease it would be seen how and when the rent is to be paid and when the lease would be liable to be cancelled have been stated. Clause 11 stipulates that at the first instance the period of lease was made 10 years and in case the Lessee acted in accordance with what was expect ed of him under clause 9	 the period of the lease 411 would be extended for a further period of 5 years upto 31st March	 1961 at enhanced rent of Rs.250 per month	 and if the Lessee continued to act in accordance with what was expected of him under clause 9 during this period of 5 years the period of the lease would be extended for a further period of 5 years	 that is	 upto 31st March	 1966 at a monthly rent of Rs.300 and in case the Lessee continued to act during this period as expected of him under clause 9 till the end of the period of 20 years he would be entitled by serving a notice to obtain an extension for a further maximum period of one year at enhanced rent of Rs.500 per month. It is pertinent to note that the word used is 'exten sion ' and not 'renewal '. To extend means to enlarge	 expand	 lengthen	 prolong to carry out further than its original limit. Extension	 according to Black 's La Dictionary	 means enlargement of the main body; addition of something smaller than that to which it is attached; to lengthen or prolong. Thus extension ordinarily implies the continued existence of something to be extended. The distinction between 'exten sion ' and 'renewal ' is chiefly that in the case of renewal	 a new lease is required	 while in the case of extension the same lease continues in force during additional period by the performance of the stipulated act. In other words	 the word 'extension ' when used in its proper and usual sense in connection with a lease means a prolongation of the lease. Construction of this stipulation in the lease in the above manner will also be consistent when the lease is taken as a whole. The purposes of the lease were not expected to last for only 10 years and as Mr. A.K. Sen rightly pointed out the Schedule specifically mentioned the lease as "for a stipulated period of twenty years. " As these words are very clear	 there is very little for the Court to do about it. The learned counsel for the appellants in support of his contention that the appellants were thika tenants refers us to ; = ; ; = ; ; ; 69C.W.N. 842; ; = ; In Kanai Lal vs Paramnidhi	 ; 	 the status of the appellants as thika tenant was not in question. The question therein was whether under Section 5(1) of the Act as amended by the Amending Act of 1953 execution proceedings taken out by the decree holder against the appellant could be entertained only by the Controller and not by the civil Courts. This Court held that Section 5(1) did not apply to a case where the landlord had already obtained a decree for ejectment against his thika tenant and consequently the civil Court had 412 jurisdiction to entertain the application. It was noted that until 1948 the rights and liabilities of the landlords and their thika tenants were governed by the provisions of the Transfer of Property Act. On October 26	 1948	 the Calcutta Thika Tenancy Ordinance XI of 1948 was promulgated because it was thought expedient	 pending the enactment of appropri ate legislation to provide for the temporary stay of the execution of certain decrees and orders of ejectment of thika tenants in Calcutta. The object of the Ordinance was to give protection to the thika tenants in Calcutta and to afford them interim relief by staying execution of certain decrees and orders as mentioned in Section 3 until an appro priate Act was passed by the Legislature in that behalf. The facts of the instant case are entirely different inasmuch as the lease was dated 26th September	 1946 and no question of eviction by executing any decree arose until the Act was passed. The only point to be noted is that the tenancy under the lease on the relevant date of creation was governed by the Transfer of Property Act. In Mahadeolal Kanodia vs Administrator General of West Bengal	 ; = ; 	 the question for decision was whether the appellant against whom proceedings for execution of a decree for ejectment was pending	 who had applied for relief under Section 28 and when that section was in force	 was entitled to have his application disposed of in accordance with the provisions of Section 28	 which had ceased to exist retrospectively though it remained undisposed on the date the Amendment Act	 1953 which omitted Section 28 of the Act	 came into force. This case is there fore of no assistance to the appellants. In Annapuma vs Tincowrie Dutt	 ; 	 it was held on the facts of the case that what was let out was land with structures and it could never come under the operation of the Act inasmuch as the property in suit had a history of 24 years under the registered lease before that claim to become a thika tenant would arise under the Act. It was also held that where there was a covenant for renewal in a lease and the option did not state the terms of the renewal	 the new lease	 if created would be for the same period and on the same terms as the original lease in respect of all the essential conditions thereof except as to the covenant for renewal itself. This case therefore is hardly relevant. In Shaffiuddin & Ors. vs G.C. Banerjee	 	 it was 413 held that the status already acquired by the tenants in Tollygunje under the West Bengal Non Agricultural Tenancy Act	 1949	 could not be prejudiced and affected by the Act and the landlords were therefore not entitled to any order of ejectment under the Act. This case has	 therefore	 no bearing. In Sheikh Gufan vs S.K. Ganguli; 	 	 the question was whether Section 30(c) of the Act was applicable to land in respect of which betterment fee was levied. It is therefore not relevant for us. We do not find any reason in the above decisions to enable us to hold that the lease in the instant case was for a period of less than 12 years and not for a period of not less than 12 years. The High Court correctly held the lease to be for the less than 12 years. The next question is that of waiver	 estoppel and res judicata. The appellants urged that there were two previous proceedings namely Misc. Execution case No. 126 of 1953 (Thika) and Misc. Judicial case No. 74 of 1958 (Thika) under the Act before the Controller. Except the implication that the proceedings having been before the Controller the re spondents treated the appellants a thika tenants	 no partic ular order finally conferring that status has been shown to us. By the order of this Court dated 10th March	 1980 in Special Leave Petition (Civil) 1363 of 1980 which was from the judgment and order dated 16.9.1979 of the High Court of Calcutta in F .A. No. 458 of 1978 the petition was dismissed "without going into the question whether the Thika Tenancy Act was applicable or not. " Misc. (J) case No. 74 of 1958 wherein the first respondent prayed for being added as petitioner No. 2 ended in a compromise. No status could	 however	 be said to have been determined. The essential element of waiver is that there must be a voluntary and intentional relinquishment of a known right or such conduct as warrants the inference of the relinquishment of such right. It means the forsaking the assertion of a right at the proper opportunity. The first respondent filed suit at the proper opportunity after the land was trans ferred to him	 and no covenant to treat the appellants as Thika tenants could be shown to have run with the land. Waiver is distinct from estoppel in that in waiver the essential element is actual intent to abandon or surrender right	 while in estoppel such intent is immaterial. The necessary condition is the detriment of the other party by the conduct of the one estopped. An estoppel may result though the party estopped did not intend to lose any exist ing right. Thus voluntary 414 choice is the essence of waiver for which there must have existed an opportunity for a choice between the relinquish ment and the conferment of the right in question. Nothing of the kind could be proved in this case to estopp the first respondent. In Shanti Devi vs A.K. Banerjee	 	 it was held that parties could not by their pleadings alter the intrinsic character of the lease or bring about a change of the rights and obligations flowing therefrom. The Court would only look into the terms of the lease irrespective of the averments in the pleadings. In the instant case as we have already held the lease to have been for twenty years	 its character could not have been changed by the pleadings	 if any	 in the above cases. Nor could the respondents be held to have waived their rights under the lease. We do not find any infirmity in the impugned High Court order on this count also. In the result	 this appeal fails and is dismissed	 but without any order as to costs. Stay order	 if any	 stands vacated. R.S.S. Appeal dis missed.

The second respondent	 who is the predecessor in inter est of the first respondent	 had on. 26th September	 1946 leased out the land in dispute to the appellant at the first instance for a period Of 10 years. The lease however provid ed to the lessee/appellants option of extension at enhanced rent	 twice for successive periods of 5 years	 and a third option of extension for a further maximum period of one year. The appellants are stated to have exercised their option of extension for two successive periods of five years	 hot failed to exercise the option of extension for one year thereafter. On that ground the first respondent instituted a suit for ejectment khas	 possession and mesne profits. The appellants	 as defendants	 contested the malt stating	 inter alia	 that they did not exercise the option for renewal after the expiry of the original tern of 10 years as they became thika tenants from 28th February	 1949 i.e. the date of commencement of the Calcutta Thika Tenancy Act	 1949 as admitted by the second respondent in two judi cial proceedings before the Controller under the Calcutta Thika Tenancy Act	 1949. It was further stated that they never paid any enhanced rent; and that the first respond ent 's claim for the differential rent was rejected in the first respondent 's suit	 and ultimately the special leave petition filed in the Supreme Court in that matter was also dismissed. 402 The suit for ejectment in the present suit was decreed by the Trial Court. The Appellate Court	 while dismissing the appellants appeal	 held that (1) the lease was for a period of 20 years and not for a period of less than 12 years	 and hence sub section 5(b) of Section 2 of the Act had no application; and (2) the respondent were not barred by waiver	 estoppel	 res judicata or principles analogous thereto because of the earlier judicial proceedings filed by the second respondent as there could be no question of giving a status under the Act when in the facts of the case such a status was not available. The High Court dismissed the appellants ' second appeal. Before this Court it was urged on behalf of the appel lants that (1) there could be no controversy about the appellants ' status of thika tenants in view of the fact that the lease was at the first instance for 10 years only and its first and subsequent extensions were contingent on the appellants regular payment of rents	 rates and taxes and enhancement of rent	 which contingency did not happen as they did not pay any enhanced rent	 but simply were holding over; (2) the second respondent admitted the Thika Tenants status of the appellants in the earlier proceedings before the Controller and were therefore estopped from questioning that status. On the other hand	 it was urged on behalf of the re spondent that the lease having clearly been for a period of 20 years	 the appellants have rightly been held not to be thika tenants under the Act; and that there could be no estoppel against a statute. Dismissing the appeal	 it was	 HELD: (1) Every contract is to be construed with refer ence to its object and the whole of its terms. The best interpretation is made from the context. The whole context must be considered to ascertain the intention of the par ties. It is an accepted principle of construction that the sense and meaning of the parties in any particular part of instrument may be collected 'ex antecedentibus et consequen tibus '; every part of it my be brought into action in order to collect from the whole one uniform and consistent sense	 if that is possible. [409E G] N.E. Railway vs Hastings	 (267)	 referred to. (2) In the construction of a written instrument	 it is legitimate and in order to ascertain the true meaning of the words used and	 if that be doubtful	 it is legitimate to have regard to the circumstances sur 403 rounding their creation and the subject matter to which it was designed and intended they should apply	 [410A B] (3) It is pertinent to note that the word used is 'exte nsion ' and not 'renewal '. To extend means to enlarge	 ex pand	 lengthen	 prolong	 to carry out further than its original limit. Extension ordinarily implies the continued existence of something to be extended. The distinction between 'extension ' and 'renewal ' is chiefly that in the case of renewal	 a new lease is required	 while in the case of extension the same lease continues in force during addi tional period by the performance of the stipulated act. In other words	 the word 'extension ' when used in its proper and usual sense in connection with a lease means a prolonga tion of the lease. [411C E] (4) Construction of this stipulation in the lease in the above manner will also be consistent when the lease is taken as a whole. The purposes of the lease were not expected to last for only 10 years as the Schedule specifically men tioned the lease as "for a stipulated period of twenty years." [411E] Kanai Lal vs Paramnidhi	 ; ; Mahadeolal Kanodia vs Administrator General of West Bengal	 ; ; Annapuma vs Tincowrie Dutt	 ; ; Shaf fiuddin & Ors. vs G.C. Banarjee	 and Sheikh Gufan vs S.K. Ganguli	 ; distinguished. (5) No particular order from the previous judicial proceedings conferring the status of thika tenants on the appellants has been shown. The special leave petition was dismissed by the Supreme Court "without going into the question whether the Thika Tenancy Act was applicable or not. " Hence	 no status could be said to have been deter mined. [413D F] (6) The essential element of waiver is that there must be a voluntary and intentional relinquishment of a known right or such conduct as warrants the inference of the relinquishment of such right. It means forsaking the asser tion of a right at the proper opportunity. [413F G] (7) Waiver is distinct from estoppel in that in waiver the essential element is actual intent to abandon or surren der the right	 while in estoppel such intent is immaterial. The necessary condition is the detriment of the other party by the conduct of the one estopped. An estoppel may result though the party estopped did not intend to lose any exist 404 ing right. Thus voluntary choice is the essence of waiver for which there must have existed an opportunity for a choice between the relinquishment and the conferment of a right in question. Nothing of the kind could be proved in this case to estopp the first respondent	 who had filed the suit at the proper opportunity after the land was trans ferred to him. [413G H; 414A B] Shanti Devi vs A.K. Banerjee	 	 referred to.