Question: When was it announced the Tennant and Piper would be returning to the show?
About the article "Doctor Who", section "Episodes".

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Mere hours after the announcement of a second series, tabloid newspapers "The Sun" and the "Daily Express" announced "exclusive" news that Eccleston had quit the series.
Eccleston then apparently released a statement through the BBC, saying that he would be leaving the role at Christmas for fear of being typecast.
Fan reaction to the news ranged from disappointment to irritation to outright anger.
Some did point out, however, that the series is uniquely suited to deal with cast changes.
The number of angry postings on the popular "Outpost Gallifrey" fan forum was enough for Shaun Lyon, the owner of the website, to close down the forum for two days to allow tempers to cool.
Speculation arose as to how long the production team had been aware of Eccleston's decision.
Eventually, it transpired that the departure had been planned and the scripts written to accommodate Eccleston's departure, but it was not meant to have been announced until after the first series had concluded.
The BBC admitted that they had falsely attributed Eccleston's "statement" and released it in violation of an earlier agreement not to reveal his departure publicly.
The statement had been made after journalists made queries to the press office.
On 16 April 2005, the BBC confirmed that David Tennant would be the Tenth Doctor.
The regeneration from Eccleston to Tennant took place in "The Parting of the Ways", the season finale.
Tennant and Piper next starred in a for Children in Need.
Tennant's first full story as the Doctor was the 2005 Christmas special, "The Christmas Invasion", and Piper joined him for the whole of Series 2.
At a BAFTA screening of "The Parting of the Ways", the finale of the 2005 series, on 15 June 2005, Jane Tranter announced that both a second seasonal episode (later titled "The Runaway Bride") and third series of "Doctor Who" had been commissioned.
Piper left the programme at the end of Series 2, and a new companion, Martha Jones (played by Freema Agyeman), joined Tennant at the start of Series 3 on 31 March 2007.
Series 2 aired in the UK and US in 2006, and finished airing in Canada on 12 February 2007.
The third series aired in the UK in the spring of 2007 and began airing in Canada and the US during the summer of that year.
A 2007 Christmas Special "Voyage of the Damned" was broadcast on 25 December 2007 in the UK, featuring Kylie Minogue as a waitress named Astrid.
The fourth series aired in the UK in 2008 featuring two companions; Donna Noble, who first appeared in "The Runaway Bride" and Martha Jones, who returned to the series for five episodes of series four.
Billie Piper also returned to the show to reprise her original role as Rose Tyler.
Following broadcast of the third series, the BBC announced that the show would not return as a weekly series in 2009, due to a number of factors.
Instead, four specials would be broadcast in 2009, with a full series returning in 2010.
It was later announced that when the full series returned in 2010, Tennant would no longer be the Doctor.
Playing the role would be the 26-year-old actor Matt Smith.
The return of "Doctor Who" has led to the BBC launching a number of spin-offs and related programmes.
The first of these was the behind-the-scenes series "Doctor Who Confidential" which began airing on BBC Three in conjunction with the 2005 series and returned for a new set of episodes in 2006; each episode focuses on elements of that week's "Doctor Who" episode, and the series has continued alongside all stories since 2005.
In 2006, the first full "Doctor Who" spin-off series, "Torchwood", debuted on BBC Three; it did not air in the United States until BBC America debuted it in September 2007, while the Canadian CBC aired it in October 2007.
A second behind-the-scenes series, "Totally Doctor Who", which aired on BBC One, also debuted in 2006.
After the appearance of Sarah Jane Smith in the 2006 episode "School Reunion", it was announced that Elisabeth Sladen would reprise the role in a new series entitled "The Sarah Jane Adventures", the first episode of which aired on BBC One on 1 January 2007, followed by its debut as a weekly series in September 2007.
Following Sladen's death, the programme came to an end after its fifth series in autumn 2011.
Yet another spin-off series, "K-9", was announced for 2007, but this series is not being produced by the BBC.
In addition, Tennant and Agyeman provided voice acting work for "The Infinite Quest", an animated serial that aired as part of the 2007 series of "Totally Doctor Who". 
In 2004, Piper appeared in the films "The Calcium Kid", as the romantic interest of Orlando Bloom's character, and "Things to do Before You're Thirty".
Shortly before starting work on "Doctor Who", she filmed a starring role in the horror film "Spirit Trap" alongside Russian pop star Alsou, released in August 2005 to generally poor reviews.
In November 2005, Piper starred as Hero in a BBC adaptation of "Much Ado About Nothing", updated for the modern day in a similar manner to the "Canterbury Tales" series in which she featured, with Hero now being a weather presenter in a television station.
"Doctor Who" originally ran from 1963 to 1989.
In the autumn of 2003, it was announced that the series would be resurrected beginning in 2005; the casting of Piper as Rose Tyler, a travelling companion to The Doctor (to be played by Christopher Eccleston), was announced in May 2004.
Piper won the Most Popular Actress category at the 2005 and 2006 National Television Awards for her work on "Doctor Who".BBC News named Piper as one of its "Faces of the Year" for 2005, primarily due to her success in "Doctor Who".
At "The South Bank Show" Awards in January 2006 Piper was awarded "The Times" Breakthrough Award for her successful transition from singing to acting.
In March, the Television and Radio Industries Club named Piper as best new TV talent at their annual awards ceremony.
In September, Piper was named Best Actress at the TV Quick and TV Choice Awards.
After the completion of the very successful first series of the revamped "Doctor Who", the British media regularly released conflicting reports about how long Piper would be staying with the programme.
In March 2006, she claimed that she would continue on "Doctor Who" into its third series in 2007.
In May, however, she was reported to be considering quitting the series, although she did express an interest in playing a female version of the Doctor in the future (possibly related to a proposed "Doctor Who" spin-off series about Rose which was later dropped).
In June, the BBC announced that she was to depart in the final episode of the second series, "Doomsday".
Piper's decision to leave had been taken a year previously, but remained a secret until news of her departure became public.
In November 2007, the BBC confirmed that she would reprise her role as Rose Tyler in the fourth "Doctor Who" series for three episodes.
Later, it was confirmed by Russell T. Davies in "Doctor Who Magazine" that this return had been planned since she left.
It was also revealed in the "Turn Left" "Doctor Who Confidential" that Billie had made arrangements to return as Rose since she decided to leave.
The series began in April 2008, and after several cameos, Piper made her official return as Rose in the series four final episodes "Turn Left", "The Stolen Earth" and "Journey's End".
She did not initially state whether she would be reprising the role again.
Interviewed on "Doctor Who Confidential", she commented that "it's never really the end for the Doctor and Rose, but it's certainly the end for the foreseeable future".
She reprised her role as Rose Tyler in "The End of Time", the last of the 2009–10 "Doctor Who" specials.
In January 2013 Piper confirmed on the Graham Norton Show that the producers had not asked her to take part in an episode for the show's 50th anniversary; however, in March 2013 the BBC announced that she would be returning to "Doctor Who" for the special alongside David Tennant, Matt Smith and Jenna-Louise Coleman. 
This was the first episode in this series which was not given a press screening prior to the broadcast.
"Radio Times" stated, "No preview tape was available for this episode."
The episode was, however, screened for BAFTA on 15 June 2005.
According to Russell T Davies in "Doctor Who Magazine", Jack was left behind because they wanted to explore the effects of the regeneration on Rose (noting that Jack would have taken the regeneration "in his stride").
Jack returned in the "Doctor Who" spin-off series "Torchwood", which began broadcast in October 2006.
In an interview in "Doctor Who Magazine", Russell T Davies stated that an alternate ending for this episode was written and filmed, with the intention that it would be shown to press previewers to hide the secret of the regeneration.
This idea was abandoned when Eccleston's departure was revealed earlier than planned.
The "false" ending would have featured similar dialogue to the televised final scene, but the TARDIS would have scanned Rose and the viewers would have seen the display read: "LIFEFORM DYING".
Davies considered this scene inferior to the one actually shown, but suggested that it might be suitable as an extra on a DVD some day.
On the DVD commentary, executive producer Julie Gardner and Billie Piper briefly discuss this ending, which Gardner describes as featuring Rose's death; unlike Davies, Gardner expresses doubts that it will be issued on DVD (it was not included in the Series 1 DVD set).
David Tennant's portion of the regeneration scene was actually filmed much later than Eccleston's, and without the presence of Billie Piper.
Tennant's segment was recorded with him speaking to a piece of sticky tape indicating Piper's eyeline and then edited into the broadcast version.
It was recorded on 21 April 2005.
Eccleston's departure had been leaked early by the BBC on 30 March 2005, who claimed that he was scared of being typecast.
On April 4 they admitted that this statement had been made without consulting the actor, and were forced to apologise.
In 2010, Eccleston denied the typecast claim, explaining that he was not comfortable in the working environment.
He later stated that he could not get along with some of the "senior people".
According to the "Sunday Mirror", an interview for BBC's "Doctor Who" website that was taken down after his departure was announced revealed that Eccleston had planned to stay for two or three more years.
Tennant was offered to replace the role when he was watching a pre-transmission copy of "Casanova" with Davies and Gardner.
Tennant initially believed the offer was a joke, but after he realised they were serious, he accepted the role and first appeared in the series finale "The Parting of the Ways".
Tennant was announced as Eccleston's replacement on 16 April 2005. 
It was announced in 2012 that Storwick would be playing the role of Piper Gray in the upcoming YTV show, Some Assembly Required.
The show premiered January 6, 2014. 
Executive producer Russell T Davies revived "Doctor Who" after a 16-year absence with the successful premiere of "Rose" in 2005.
Following the BBC's announcement of a second series being commissioned, the story broke that Christopher Eccleston, who played the titular Ninth Doctor, would not be returning for the second series.
On 16 April 2005, the BBC announced that David Tennant had been selected for the role of the Tenth Doctor.
His first appearance in the series was for 20 seconds following the Ninth Doctor's regeneration at the end of "The Parting of the Ways".
His first full episode as the Doctor, barring an appearance in a "" during the 2005 Children in Need show, was the 2005 Christmas Special, "The Christmas Invasion".
He then appeared in the 2006 series, the second Christmas Special, the 2007 series, the third Christmas Special, and the 2008 series.
Rather than a traditional series run, 2009 features a series of five specials and a series of animated shorts, all starring Tennant as the Tenth Doctor; he also guest-starred in a two-episode serial of "The Sarah Jane Adventures" spin-off in that year.
Tennant also appears in two animated serials; "The Infinite Quest" is counted with the third series, and "Dreamland" is counted amongst the 2008–10 specials.
In 2013, Tennant reprised his role as the Doctor for the 50th anniversary special "The Day of the Doctor", in which it is revealed that due to an uncounted past incarnation, the Tenth Doctor is in fact the Doctor's eleventh incarnation.