The TARDIS materialises on Spiridon, where the Doctor and Jo are aware a Dalek plot is afoot. Teaming up with a band of Thals, the time travellers soon discover an enormous army of Daleks is present on the planet. To make matters worse, a Dalek scientific team is on the verge of gifting their siblings with the invisibility powers of the Spiridon natives.

In early 1972, producer Barry Letts and script editor Terrance Dicks decided that part of Doctor Who's celebratory tenth season should be an epic story rivalling in duration the longest serial to date, the twelve-part The Daleks' Master Plan from 1965/66. Later realising that a single three-month serial would be difficult for viewers to follow, they opted instead to devise two linked six-part adventures. Each story would feature one of the Doctor's two greatest foes: first the Master (in Frontier In Space, written by Malcolm Hulke) and then the Daleks.

The Daleks had returned to Doctor Who after a lengthy absence in Season Nine's Day Of The Daleks. The serial's development had brought Letts and Dicks in touch with the monsters' creator, Terry Nation. Nation had not written for Doctor Who since The Daleks' Master Plan, and his last contact with the show's production team had been in 1967 when he refused permission for a story in which the Daleks appeared alongside the Cybermen. In agreeing to allow the Daleks to return in Day Of The Daleks, however, Nation had obtained from Letts and Dicks a first refusal on writing any future Dalek stories.

As it happened, the production team's inquiries about a Dalek story for Season Ten coincided with a lull in Nation's workload, and so he elected to tackle the scripts himself. A storyline was commissioned under the title Planet Of The Daleks on April 21st; by the time the six scripts were requested on May 11th, the serial had been given the name “Destination Daleks”.

One of the lead characters, Rebec, was christened after Nation's daughter Rebecca. Another character, Petal, had his name reversed to Latep to avoid confusion with Patel from Frontier In Space. The planet was called Destinus before becoming Spiridon. Nation was unsure how many Dalek casings would be available to the production team: he originally envisioned both Rebec and Codal masquerading as Daleks, for instance. Plans to kill off all the Thals at the end of episode four were abandoned, partly to avoid the disapproval of Ronnie Marsh, Head of Drama Serials. Also dropped were the individual episode titles Nation employed (as he was unaware that their use had been discontinued in Doctor Who in mid-1966). Latterly, the first episode of “Destination Daleks” was heavily rewritten by Dicks to bring it in line with the revised ending of Frontier In Space, with the Doctor injured and unconscious.

Assigned to direct “Destination Daleks” was David Maloney, another Doctor Who veteran whose last work on the programme had been The War Games three and a half years before. For the first time since 1964, four new Daleks were constructed to join the three which had been retained from the Sixties. Maloney was disappointed to discover that these were of generally inferior workmanship, however, and so elected to keep them in the background as much as possible. For the Dalek Supreme, Nation suggested using a refurbished casing from the feature film Daleks -- Invasion Earth 2150 AD which he had been given.

Just before location filming began, the title of the story -- allocated the production code Serial SSS -- reverted to Planet Of The Daleks. Only one site was visited, with Beachfields Quarry in Redhill, Surrey posing as the ice pool on January 2nd and 3rd, 1973. Four days at the Ealing Television Film Studios followed on the 4th, 5th, 8th and 9th, concentrating on sequences in the chimney and the ice tunnels. Model shots were captured on January 16th.

As usual, studio recording for Planet Of The Daleks took place on fortnightly Mondays and Tuesdays, beginning on January 22nd and 23rd. Unfortunately, Katy Manning had her hair cut shortly before these dates, meaning that Jo's appearance in the filmed material is somewhat different from the videotaped sequences. These first two days, which were allocated to Television Centre Studio 4, saw the recording of most of episodes one and two, as well as the Doctor and Jo's final scenes for part six. Maloney also recorded some material which would be incorporated into the last installment of Frontier In Space and form its new ending.

More model filming occurred on January 27th and 29th. The second studio block then took place on February 5th and 6th, this time in TC6. Most scenes from episodes three and four were completed, as well as the Dalek control room sequence for part two and the rocky area for part six. The 8th was another model filming day, and the serial was completed on February 19th and 20th in TC1. Although episodes five and six were the main concern, several inserts for other installments were also recorded at this time.

• Doctor Who: The Handbook: The Third Doctor by David J Howe and Stephen James Walker (1996), Virgin Publishing, ISBN 0 426 20486 7.
• Doctor Who: The Seventies by David J Howe, Mark Stammers and Stephen James Walker (1994), Virgin Publishing, ISBN 1 85227 444 1.
• Doctor Who Magazine #202, 4th August 1993, “Archive: Planet Of The Daleks” by Andrew Pixley, Marvel Comics UK Ltd.
• Doctor Who Magazine Special Edition #2, 5th September 2002, “Saturday Night's Alright For Fighting” by Andrew Pixley, Panini Publishing Ltd.