Question: When did the network announce that the show would feature Tennant and Piper again?
About the article "Doctor Who", section "Episodes".

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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. 
In "The Day of the Doctor", Smith and Coleman star alongside David Tennant and Billie Piper; Tennant reprised his role as the Tenth Doctor, while Piper, although credited as playing Rose Tyler, in fact portrays a manifestation of "The Moment", a Gallifreyan super-weapon, that has taken on Rose's form.
The casting of Tennant and Piper was announced by the BBC on 30 March 2013.
Photographs of Smith, Tennant and Coleman at the first read-through were published, which also confirmed the casting of "Gavin & Stacey" star Joanna Page.
On 8 April 2013, the BBC announced that Jemma Redgrave would reprise her role as Brigadier Lethbridge-Stewart's daughter Kate Stewart from "The Power of Three".
Rumours had also circulated that Christopher Eccleston would have some involvement; Eccleston had some discussions with Steven Moffat, but eventually declined to return as the Ninth Doctor.
Sylvester McCoy, who played the Seventh Doctor, claimed that none of the surviving actors who portrayed the Doctor prior to Eccleston had been contacted regarding the special.
Despite stating that it would be "a travesty" if his character did not feature in the special, John Barrowman did not feature as Captain Jack Harkness.
The release of "The Night of the Doctor" on the 14th November revealed that Paul McGann had returned to portray the Eighth Doctor.
On 1 June 2013, Matt Smith announced that he would be leaving "Doctor Who", with his final episode being the 2013 Christmas Special, with that episode set to feature the Doctor's latest regeneration.
Speculation about the identity of the actor set to take over began immediately, with a number of names suggested.
The official announcement of the actor of the Twelfth Doctor was made in a special live simulcast on 4 August 2013 in "Doctor Who Live: The Next Doctor", and saw confirmation of Peter Capaldi in the role.
The 2013 special is the fourth and final Christmas episode to feature Matt Smith's incarnation of the Doctor, and the second to feature Jenna Coleman as Clara Oswald. 
Later in 1996, Piper joined World Championship Wrestling (WCW).
He appeared at Halloween Havoc to "break Hogan's monotony."
In his first appearance, Piper asked Hogan, "Do you think fans would've loved you so much, if they hadn't hated me?"
Piper and Hogan wrestled in a non-title match in the main event of Starrcade, WCW's biggest pay-per-view event of the year.
Piper defeated Hogan with a sleeper hold.
Piper faced Hogan in a title match at SuperBrawl VII.
This time, Hogan beat Piper when Randy Savage interfered and joined the New World Order (nWo).
Promos showed Piper locking himself in the Alcatraz prison and vigorously exercising in order to prepare for the highly anticipated match.
During the spring of 1997, Piper joined forces with Ric Flair and The Four Horsemen in their battle with the nWo.
Shortly thereafter, Piper and Flair feuded before Piper disappeared from the scene.
Piper briefly returned in October 1997 to face Hogan once again in a steel cage match, which Piper did win.
In early 1998, Piper once again returned to feud with Hulk Hogan, Randy Savage, and Bret Hart.
In early 1999, Piper had a short run as United States Champion, became WCW Commissioner, and resumed his feud with Flair over control of WCW.
Piper also had a short feud with Buff Bagwell in the summer of 1999, where he was defeated by Bagwell, whose mother got involved.
In late 1999, Piper was featured on WCW Television, in an angle with Vince Russo, who was now portraying himself as the "Powers That Be" (an unseen power that was controlling WCW).
At Starrcade, Piper was the special referee in the WCW title match featuring Goldberg and Bret Hart.
This match was otherwise notorious for Goldberg legitimately injuring Bret Hart, giving him the concussion that would eventually lead to his retirement.
Forced by Russo, Piper called for the bell when Hart locked in the Sharpshooter on Goldberg, when it was apparent that Goldberg had not submitted.
Piper apologized for this incident the next night on "Nitro" and attempted to make the save for Goldberg when Bret Hart and the nWo beat him down, but the nWo also attacked Piper.
The feud between Piper and the Powers That Be ended shortly after and Piper disappeared.
Piper's last appearance in WCW was at SuperBrawl in February 2000 where he was a surprise referee in the title match between Sid Vicious, Jeff Jarrett and Scott Hall.
In the fall of 2000, WCW terminated Piper's contract, and the organization ceased to exist after being sold to WWF in March 2001.
Before going to the WWE in 2003 Piper was the figurehead and commissioner of the now defunct XWF promotion featured in its earliest live events.
(Indiana, Milwaukee, Green Bay) 
"Doctor Who" actor David Tennant, a regular on the show and a friend of O'Connell, has been involved in some of the show's and O'Connell's professed "shabbiest" moments including the 2006 Christmas panto with Thandie Newton and the axed Mr. T escapade.
In late March 2007 he appeared on the Breakfast show again and took part in another escapade "1 Golden Square" (the address of Absolute Radio).
Later that week when he appeared on a rival show on BBC Radio 1 on the Saturday, Virgin Radio producer Roque Segade-Vieito contacted the station for a practical joke texting a question to Tennant as "I hear you have been signed up for a new programme called 1 Golden Square".
Ironically, the question was taken seriously and addressed to Tennant live on Radio 1 leaving O'Connell rather pleased with the gag.
In November 2009, Tennant co-hosted the Absolute Breakfast Show with O'Connell for three consecutive days.
In October 2010, Tennant co-hosted with O'Connell and acted out Copacabana with some of the Breakfast Show team to discover "just who shot who".
Something with had been debated for a few days prior to this.
In September 2011, Tennant again co-hosted with O'Connell and experienced a fish-facing with a trout, as well as a tennis ball challenge outside the Absolute Radio studios. 
In an interview with "SFX" producer Phil Collinson stated that after the Doctor regenerates the "initial dynamic changes because has to learn to trust him again".
Piper added that as the Doctor is incapacitated Rose consequently feels "unloved", "isolated" and "like she's lost her best friend".
In the Doctor's absence Rose relies on her observations of him and tries to mimic his actions.
Collinson felt it was important to resolve any mistrust between the pair by the end of the Christmas Special, as the public had responded well to Rose and the Doctor's friendship previously.
Davies had scripted dialogue in "The Christmas Invasion" explaining the newly regenerated Doctor's estuary English accent by stating he had imprinted on Rose and adopted her way of speaking.
However, due to time constraints this sequence was not filmed.
Discussing how Rose had developed by the second series, Piper described her as having "come on in leaps and bounds" and stated she is now "a lot more proactive."
She felt that there is a "different kind of energy" between Rose and the Tenth Doctor, whilst Tennant remarked that the audience would get to see the Doctor-companion relationship "developing and becoming something that it maybe hasn't before."
Piper stated that with the Tenth Doctor, Rose is "more tetchy and more possessive" over him as "she feels like she's lost him once and doesn't want to lose him again".
She cited Rose's "catfight" with former companion Sarah Jane Smith in "School Reunion" as evidence of this.
Discussing the possibility of Rose and the Tenth Doctor becoming more romantically involved Piper stated "You want it to happen, but at the same time you don't want it to happen".
Tennant likened the dynamic between the pair to that of Dana Scully (Gillian Anderson) and Fox Mulder (David Duchovny) in "The X-Files".
Both Tennant and Piper agreed that the expectation of the relationship is more exciting than having it realised.
To add to the tragedy of their separation, Davies scripted the series two story arc so that Rose and the Doctor would be indirectly responsible for their separation.
"It's deliberate when that happens [the Doctor and Rose's arrogance", said Davies, "and they do pay the price.
In "Tooth and Claw", they set up the very thing — Torchwood — that separates them in the end.
It's sort of their own fault."
Though Davies left the Doctor's response to Rose's declaration of love in "Doomsday" unstated, Gardner felt strongly that the character reciprocated her feelings.
On the commentary for the episode she stated that she would "confirm to the world" that he was going to "say it back.
"Davies created the expectation of Rose's return in the fourth series by mentioning her in dialogue and featuring Piper in cameo appearances in "Partners in Crime", "The Poison Sky", and "Midnight".
Speaking on how Rose's character had changed between her appearances, Davies described the fourth series Rose as "tougher, more independent, and might, at times, seem a little harder".
Piper stated she rewatched her earlier episodes to remember how the character spoke and acted as she felt she had "been playing posh birds" since she left the programme and by contrast "Rose is a bit of a chav".
Rose is re-united with the Doctor near the climax of "The Stolen Earth".
Director Graeme Harper insisted that the scene appear "mystical" because the characters' reunion was "the most magical moment" in the entire episode and Ernie Vincze, the Director of Photography for the show, compared the scene's feeling to the 1980s science-fiction film "Blade Runner".
Davies characterised the reunion between Rose and the Doctor as "the biggest romance [the viewer has ever seen" and joked that seminal films such as "Gone with the Wind" should have ended with a Dalek shooting the male lead.
He had difficulty splitting up the characters for a second time for the necessity of the plot.
He felt that "Rose has to be stupid to fall in love with Doctor #2" because "she's doing what the plot demands, not what she'd demand".
At one stage he considered giving an explanation that Rose's dimension hopping and the Dalek's meddling with reality had contaminated her with "voidstuff" and that she would die if she stayed in her original universe.
In the final episode it is enough for her to stay that the human Doctor needs her and is able to reciprocate her love.
Porter felt that the climax of "Journey's End" indicated that "Rose's role as a sidekick has been completed" as she has a second Doctor to humanise, one who she can be equals with.
Piper's 2010 appearance in "The End of Time", Tennant's final story as a series regular, was leaked by the press in May 2009 when Piper was seen photographed on location with Coduri and Tennant.
Though Davies had intended the serial to end with the Tenth Doctor visiting his former companions, he struggled with how to include Rose.
An initial idea was for Rose to appear with her part-human Doctor in the parallel universe, where both would sense the original Tenth Doctor regenerating.
However, Davies felt this would raise too many questions about their lives in the parallel universe.
Davies' successor as executive producer, Steven Moffat, felt that Davies ended Rose's story in the perfect way by choosing to take it back to the beginning of her acquaintance with the Doctor.
Piper's return for "Doctor Who"s 50th anniversary episode was confirmed in March 2013.
Moffat wished to include Piper in the episode because he felt that she symbolised the rebirth of "Doctor Who".
As he did not feel comfortable adding to Davies' story arc, he chose instead to re-introduce her Bad Wolf persona.
During the episode Piper's character has dialogue solely with John Hurt's War Doctor, and is unseen by the other characters, including the Tenth Doctor.
Reviewers noted similarities between the characterisation of Bad Wolf Rose and that of a plot device used by Charles Dickens in his 1843 novella "A Christmas Carol".
Ted B. Kissell, a journalist for "The Atlantic" likened the War Doctor to Ebenezer Scrooge and dubbed Rose the "Ghost of Doctors Yet to Come".