The Doctor, Jamie and Zoe believe the TARDIS has brought them back to Earth, in the midst of World War One. But it soon becomes apparent that they are nowhere of the sort. In fact, a race of aliens has been kidnapping soldiers from various points in the Earth's history and transporting them to another planet, with the intention of using them to form the greatest army the universe has ever seen. At the helm of this plot is the War Chief, a renegade Time Lord like the Doctor. To stop him, the Doctor may be forced to call upon his own people and give up his wandering in time and space forever.

The story originally intended to bear the designation of Serial ZZ was “The Impersonators”, the storyline for which was commissioned on July 5th, 1968. The author of this six-part adventure was Malcolm Hulke, who had cowritten The Faceless Ones with David Ellis two years earlier. About a month later, Patrick Troughton informed the Doctor Who production team that he wanted to leave the show at the end of the next recording block. It was therefore decided that “The Impersonators” would be Troughton's penultimate story.

The era of the Second Doctor would then conclude with a four-part Serial AAA, to be written by Derrick Sherwin. Sherwin was in the process of handing over the script editor's job to Terrance Dicks while taking over the producer's duties from Peter Bryant. Sherwin's story seems to have been planned from around October 1968, with Troughton contracted for these final four episodes on November 4th. It was also known that Frazer Hines would be leaving Doctor Who at the same time, but Bryant and Sherwin hoped to persuade Wendy Padbury to remain for Season Seven. The new year would not only see Doctor Who broadcast in colour for the first time, but would also feature a new format in which the Doctor was marooned on modern-day Earth. This was inspired by the recent success of stories such as The Web Of Fear and The Invasion, and Sherwin's serial would establish the new status quo.

Unfortunately, as 1968 drew to a close, it appears that problems were developing with both “The Impersonators” and Sherwin's story. In November, it was decided to instead conclude Season Six with a mammoth ten-part Serial ZZ -- the longest story attempted by Doctor Who since the twelve-episode The Daleks' Master Plan three years earlier. “The Impersonators” was formally abandoned on December 30th, but by this time, Hulke had already been asked to collaborate with Terrance Dicks on the new season finale. Called The War Games, this was commissioned on December 23rd. It was planned that, in addition to setting up the new format for Season Seven, The War Games would shed light on the Doctor's origins by introducing his own race, the Time Lords. Troughton's imminent departure was announced to the press on January 7th, 1969.

With production due to begin in less than three months, Dicks and Hulke worked extremely quickly on The War Games, yet only a few minor changes ended up being made to their scripts. Amongst these, Spencer and other, unnamed resistance fighters were intended to die in the alien attack in part five. Also in this episode, Zoe originally misidentified the meaning of TARDIS as “Time And Relative Dimensional Intergalactic Ship”. Von Weich was to have been shot trying to escape at the end of the installment, and Jennifer Buckingham was present when Jamie and the others were ambushed. By the time part six was delivered, however, it had already been decided that Jennifer would not be included in the second half of the story.

In episode seven, Smythe's aide was initially a new character called Sergeant Wilkins; only latterly was the decision made to bring back Sergeant Major Burns from the first installment. The script for part eight implied that the alien race controlling the Zones was collectively called the War Lords -- an identification not made in the completed programme -- and also included a line of dialogue in which the Doctor asserts that there are multiple time-travelling civilisations. In part nine, the Doctor defined the Time Lords as being the leaders of his race. Episode ten included a prominent role for an unseen Time Lord judge, most of whose dialogue was later allocated to the First Time Lord. The means of the time travellers' last-ditch attempt to escape from their Time Lord sentence was also different. Rather than verbally duping the Time Lord into switching off the force field, the Doctor and Jamie took advantage of a weakening of the barrier near the floor to push Zoe through, enabling her to turn off the field.

By now, it was known that Padbury would in fact be leaving Doctor Who alongside Troughton and Hines at the conclusion of The War Games. On January 27th, she was booked for her final serial, and the public was informed of her decision on February 24th. Meanwhile, David Maloney -- who had recently completed The Krotons -- was appointed the director of The War Games. It was Maloney who suggested that the alien mesmerism should be manifested by the officers putting on spectacles; Dicks and Hulke had originally conceived them as speaking in a cold “alien voice” when exercising the mind control. It was also Maloney who came up with the sequence in which the Doctor sends his plea to the Time Lords in a small box, and who suggested war settings which would be interesting to the viewers after seeking advice from his young son.

Because of the length of The War Games, two weeks of filming were necessary rather than the standard one. However, with the studio sessions for each episode scheduled to take place just over a week prior to broadcast, this meant that the extra filming would have to occur during the week in which the final installment of the previous story, The Space Pirates, was in studio. As a result, Troughton, Hines and Padbury had to prefilm all their scenes for that episode.

Filming for Serial ZZ began on March 23rd, with the start of four days at the Sheepcote Rubbish Tip in Brighton, East Sussex; this posed as the No Man's Land, as well as the Scottish locale to which Jamie was returned by the Time Lords in part ten. Amongst the cast joining The War Games at this point was Derrick Sherwin's wife, Jane Sherwin, playing Lady Jennifer Buckingham. The venue on March 27th was the Seven Sisters Country Park at Exceat in Seaford, East Sussex, where the Roman Zone material was enacted. On the 28th, Underhill Lane in Clayton, West Sussex was the locale for the episode four scenes in which Jamie and Jennifer are captured by the Confederate soldiers.

After a day off, work resumed on March 30th at locations in West Dean, East Sussex for various roadway scenes. More of these were completed the next day, at High Park Farm in Exceat and at Underhill Lane. Finally, Birling Manor Farm in East Dean was the setting of material in the chateau courtyard, the prison and the Crimean Zone. On April 3rd, a day was spent at the Ealing Television Film Studios; amongst the effects completed was the shot of the Doctor's face on the Time Lord screen -- splitting up, spiralling and eventually fading away -- which would conclude the Troughton era.

Studio recording began on April 11th. The initial four episodes were recorded on consecutive Fridays, with the first five installments all taped in Doctor Who's regular home of Television Centre Studio 4. Amongst the characters referred to (but not seen) in part one was a Major Ellis, whom Hulke had named after his writing partner on The Faceless Ones. This would also be the first Doctor Who episode for which Sherwin received a producer's credit; with Dicks having coauthored the serial, no script editor would be listed.

Starting with part five on May 8th, the recording day was shifted back to Thursday. Then, for episode six on May 15th, recording moved to TC8. The role of Private Moor in this installment appears to have written expressly for Patrick Troughton's son David, who had previously had an uncredited appearance on The Enemy Of The World.

Meanwhile, Bryant and Sherwin were attempting to find a new actor to play the Doctor. They originally considered Ron Moody, who had played Fagin in the 1968 feature film Oliver!. Bryant and Sherwin thought that a similar type of character might be appropriate for the Third Doctorm but Moody turned down the role. BBC Head of Drama Shaun Sutton approached Stratford Johns, who was best-known for playing Charlie Barlow in Z Cars and Softly Softly: Task Force. Johns, however, feared that Doctor Who would be too strenuous and declined.

Shortly thereafter, however, Bryant was contacted by Richard Stone, the agent for character actor Jon Pertwee. Best known for his comedy roles, Pertwee had appeared in dozens of movies, including several installments of the Carry On franchise and A Funny Thing Happened On The Way To The Forum, but was not a total stranger to more serious parts -- at the time, he was preparing for a role in the Amicus horror film The House That Dripped Blood, and he had previously recorded a guest appearance in The Avengers. However, Pertwee was most popular for the radio show The Navy Lark which he created and had been starring in since 1959.

Although Pertwee's first wife, Jean Marsh, had appeared in Doctor Who in 1965's The Crusade, it was fellow Navy Lark actor Tenniel Evans who encouraged Pertwee to ask his more dubious agent to inquire about playing the new Doctor. Much to Pertwee's surprise, Stone informed him that he was already on Bryant's shortlist. After meeting with BBC Head of Drama Shaun Sutton, Pertwee agreed to a contract for Season Seven on May 21st, ensuring that he would appear in at least twenty-one episodes of Doctor Who.

The day after, The War Games part seven was taped in TC1. Another Doctor Who family connection was in evidence during this recording, as Maloney had cast Peter Craze as Du Pont. Craze was the brother of Michael Craze, who had played the Doctor's companion Ben Jackson during Seasons Three and Four; Peter Craze had also appeared in The Space Museum. As the War Lord, Maloney cast Philip Madoc, whom he had used on The Krotons. To disguise the fact that he had only recently appeared in Doctor Who, Madoc quickly grew a beard, and was given thick glasses to wear.

The War Games continued to bounce between studios for its final three installments: part nine was recorded in TC6, while the eighth and tenth episodes went before the cameras in TC8. For the final episode, taped on June 12th, Clare Jenkins returned to her role of Tanya Lernov from The Wheel In Space for the scene where Zoe is transported back home by the Time Lords. Several monsters also made cameo appearances, including a Dalek, a Cyberman, an Ice Warrior, a Yeti and a Quark; a Kroton was intended to feature, but the costume was found to be in a state of disrepair. The Yeti was played by John Levene, who had recently played Corporal Benton in The Invasion.

Episode ten also saw the inclusion of two clips from past serials: fifteen seconds of the TARDIS materialising on the sea from Fury From The Deep part one and five seconds of the Ship in space from The Web Of Fear part one were both incorporated into the sequence where the Doctor tries to flee from the Time Lords. An establishing shot of Space Station W3 from the first installment of The Wheel In Space was also used in the episode's closing stages.

The completion of The War Games brought both Season Six and the sixth production block to an end; for the first time, no serials would be taped at the end of the recording block and held over to start the next season. Part ten was broadcast nine days later, on June 21st; this was in the wake of the announcement made on the 17th that Jon Pertwee would play the Third Doctor.

Not long after leaving Doctor Who, Frazer Hines was cast as Joe Sugden in the soap opera Emmerdale Farm. Hines remained on the programme for twenty-two years until 1994, by which time it had become known simply as Emmerdale. Nonetheless, he took up his kilt twice more, playing Jamie in both The Five Doctors and The Two Doctors. Hines has also recorded linking narration for a number of BBC Audiobooks releases of incomplete Doctor Who stories.

Wendy Padbury's career continued apace, with numerous roles on stage and radio, in addition to TV appearances including Freewheelers and alongside Hines in Emmerdale Farm. She also appeared in the horror film Satan's Skin (also called Blood On Satan's Claw). Amongst her theatrical appearances was the 1974 play Doctor Who And The Daleks in Seven Keys To Doomsday, in which she played companion Jenny to Trevor Martin's putative Fourth Doctor. Following her marriage in the Seventies, Padbury divided her energies between her family and her career, although she found time to return to Doctor Who as Zoe in The Five Doctors. Padbury largely gave up acting in the early Nineties to become a theatrical agent, numbering amongst her clients Nicholas Courtney, who played the Brigadier. Nonetheless, she tackled the role of Lorraine Baynes in the Sixth Doctor audio drama Davros from Big Finish Productions.

After his departure from Doctor Who, Patrick Troughton scarcely found himself at a loss for work. He appeared in several feature films, including The Omen with Gregory Peck and as the time-travelling Professor Wagstaffe in A Hitch In Time. Troughton also garnered numerous television roles in productions as varied as The Six Wives Of Henry VIII, Coronation Street, The Box Of Delights and Knights Of God. He made no less than three return appearances in Doctor Who, in The Three Doctors, The Five Doctors and The Two Doctors. He also harbored an ambition to secretly play a monster in costume, but sadly this desire would go unfulfilled. Patrick Troughton died on March 28th, 1987 of a heart attack in his hotel room while attending a science-fiction convention in Columbus, Georgia. It was one of many such events Troughton attended during the Eighties, during which he demonstrated that -- despite his private and retiring personality -- he harboured an abiding love for both Doctor Who and its fans.

• Doctor Who: The Handbook: The Second Doctor by David J Howe, Mark Stammers and Stephen James Walker (1997), Virgin Publishing, ISBN 0 426 20516 2.
• Doctor Who: The Sixties by David J Howe, Mark Stammers and Stephen James Walker (1992), Virgin Publishing, ISBN 1 85227 420 4.
• Doctor Who Magazine #232, 22nd November 1995, “Archive: The War Games” by Andrew Pixley, Marvel Comics UK Ltd.
• Doctor Who Magazine Special Edition #4, 4th June 2003, “Paradise Lost” by Andrew Pixley, Panini Publishing Ltd.