This story was the result of a return to the programme by Christopher H Bidmead, a former Doctor Who Script Editor, who contacted the production office in the summer of 1982 about writing a new script. Christopher H Bidmead’s last contribution to the show had been Peter Davison’s debut story - the 1982 story "Castrovalva".
It has been reported that Christopher H Bidmead was happy to return to Doctor Who, but was rather more dubious about Producer John Nathan-Turner’s desire to feature monsters heavily in Season Twenty One.
It has been revealed that Christopher H Bidmead conceived the gravity-controlling Tractators which were inspired by wood lice which had infested the garden of a former residence and the desolate, Blitz-like setting was influenced by reports of fighting in Beirut at the time.
The original title of this story was "The Wanderers". Various other titles noted in BBC documents include "Frontious", "Froutious" and "The Frontios" but these are almost certainly misspellings or misprints.
One concept, devised by Christopher H Bidmead, which did not make it past the scripting process was the Gravis was to be accompanied by a translator built out of colonist body parts. However, director Ron Jones - making his first Doctor Who story since "Arc of Infinity" a year earlier - objected, believing that it would limit his selection of shots, and would require considerable effort to achieve with little substantive gain.
Early on, it had been decided that this story would be entirely studio-based so as to save money for more expensive stories to follow. These being "Resurrection of the Daleks" - an action packed Dalek story - and "Planet of Fire" - Doctor Who’s third story to be filmed overseas (this time in Spain).
One of Ron Jones’ key guest performers for this story was veteran actor Peter Arne, who had appeared in more than fifty feature films, including Return of the Pink Panther, Chitty Chitty Bang Bang as well as several guest roles on The Avengers. However, just prior to the start of recording he was discovered murdered at his home. Peter Arne had been cast to play the part of Range. Ron Jones was therefore forced to hastily recast the role, hiring William Lucas to replace Peter Arne.
Peter Arne’s death was not the only tragedy to befall this story. About a month earlier, designer Barrie Dobbins had committed suicide after accomplishing much of the preparatory work. Barrie Dobbins’ assistant, David Buckingham, therefore finished "Frontios" in his place.
Peter Gilmore, well known for his starring role as sea captain James Onedin in the BBC’s period drama serial The Onedin Line, plays Brazen.
Jeff Rawle, one of the stars of the Channel 4 comedy show Drop the Dead Donkey, is seen here in the very different role of the colony’s deputy leader, Plantagenet. Jeff Rawle also later played Mr. Harding The Sarah Jane Adventures story "Mona Lisa’s Revenge".
Lesley Dunlop later played the part of Susan Q in the 1988 Seventh Doctor story "The Happiness Patrol".
John Beardmore appeared uncredited as Captain Revere.
Just prior to the recording of this story, in August 1984, John Nathan-Turner held a press conference to unveil the actor who would replace Peter Davison as The Doctor. This was Colin Baker who would be joined by Nicola Bryant as new companion Peri Brown near the end of Season Twenty One.
Recording of this story proceeded smoothly except when it came to the scenes with the excavation machine. Christopher H Bidmead had envisaged this as being entirely fabricated out of human remains, much like his unused translation machine. This concept however, had already been scaled back to make it less gruesome, but Ron Jones was nonetheless unhappy with visual effects designer Dave Havard’s creation, and shot around it as much as possible.Much as they had on "Warriors of the Deep" costume woes plagued "Frontios". In Christopher H Bidmead’s original conception of the Tractators, they were able to curl up into a ball, and would kill their victims by encircling and smothering them. To achieve this the actors hired to play the Tractators were all trained dancers. Unfortunately, Costume Designer Anushia Nieradzik’s completed outfits were very constraining and inflexible and so did not allow for this movement. This forced Ron Jones to abandon these plans. Also between takes the actors had to be fed oxygen via a tube under the base of their costumes, as they were insufficiently ventilated for the hot conditions of the studio recording.
The helmets worn by Brazen’s guards were originally used, as the helmets of the Federation troops, in Blake’s 7.
Episode one, which ran almost nine minutes overtime, was cut heavily including sequences that were later referred to in the text (such as the Gravis’ knowledge of The Doctor and that The Doctor and Tegan Jovanka’s voices echoed through the Tractators’ tunnels). Much of the cut scenes involved Cockerill and explored his deepening sense of rebellion, such as by allowing Tegan, Vislor Turlough and Norna to skulk about the colony without alerting Brazen. Another cut scene saw Tegan and Turlough return to the TARDIS to find it surrounded by curious colonists. Turlough later refers to this in a segment retained for broadcast when he remarks that they've lost their ‘news value’.
For the first time in many years, The Doctor is heard to refer to TARDIS as standing for ‘Time and Relative Dimension in Space’.
The TARDIS hat stand makes a re-appearance and at one point Turlough brandishes it as if it is a weapon. He then gives it to Plantagenet as a gift.
Despite being introduced in "The King's Demons", as a new companion, Kamelion again is not referenced or seen in this story.
Turlough is heard to state that the Arar Jecks of Heiradi hollowed a huge subterranean city beneath their planet during the Twenty Aeon War. He also recognises signs of the Tractators from his home planet. This is the first time that a solid reference is made to Turlough’s home planet.
It is revealed that Turlough’s home planet was attacked millennia ago by Tractators - an event that was locked into their ancestral memory. The sight of the Tractators triggers a memory resurgence which causes Turlough to go into catatonic shock. Gradually he recalls more and more of these memories, which allow him to remember who the Tractators were, what their goals were - and more importantly, how to defeat them.
This story remains, to date, the sole appearance of the Tractators in the television show.
The Gravis knows The Doctor and the capabilities of a TARDIS, presumably by reputation. The Doctor leaves the Gravis on the uninhabited planet Kolkokron and without his influence the Tractators become little more than harmless burrowing creatures.
This story contains a number of errors. Namely: In the opening scene, as Captain Revere sees the earth moving beneath him, the fingers of one of the technical crew are visible giving it a helping hand; When the TARDIS explodes, what happens to Kamelion?; When Tegan traps Brazen in the medical unit, she puts a bar across the middle of a door handle. By the next scene it has moved to the top of the handle.
A curious myth has since sprung up, amongst Doctor Who fandom, that this story was originally intended to feature Richard Hurndall in a black and white flashback remembered by Peter Davison's Doctor after hitting his head on the TARDIS control console. It has since been revealed that this was never intended.
The show’s timelines often state the colonies in this story and the 1966 First Doctor story "The Ark" are from the same exodus from Earth, and that both stories may in fact take place simultaneously.
The final moments of this story, where the TARDIS is dragged into a time corridor, is a lead into "Resurrection of the Daleks". It was rewritten by Eric Saward, so as to provide a cliffhanger into the next story, and actually appears the way it was originally scripted at the end of "The King's Demons" which would have led into that story had "Resurrection of the Daleks" stayed in its original slot of being the final story of Season Twenty.
The transmission of the final episode was followed by a trailer of clips for the following story, "Resurrection of the Daleks".
The short story "Life After Queth" (published in the Big Finish Productions book "Short Trips 16: Farewells") details an adventure The Doctor, Tegan and the Gravis had on the way to Kolkokron.
The Big Finish audio story "Excelis Dawns" details an adventure The Doctor had on the way back to Frontios. It occurs between the end of this story and the scene which continues into "Resurrection of the Daleks".
This story was novelised by Christopher H Bidmead and published by Target Books in December 1984. This novelisation includes many gruesome images of the Tractators technology including a hovering translation device. The cliffhanger that led into "Resurrection of the Daleks" is also removed.
"Frontios" was Christopher H Bidmead’s last televised Doctor Who work. Later in 1984 He was approached to see if he would be interested in writing a new story teaming the Tractators with The Master which would likely have been included in the original version of Season Twenty Three. But all the stories planned for that season were scrapped in the wake of Doctor Who's eighteen-month hiatus in 1985 and 1986. This lost story however, is brought back to life (minus The Master) in the Big Finish Productions audio story "The Hollows of Time".
Christopher H Bidmead was also asked to write a story for the new Season Twenty Three entitled "The Last Adventure" (later called "Pinacotheca"). Eric Saward however, was unhappy with Christopher H Bidmead’s submission and so it was abandoned in early 1986. Since then, Christopher H Bidmead has continued to work as a freelance writer, with an emphasis on articles for computer and technology-related journals.
The first time in many years, The TARDIS is refered to as standing for ‘Time and Relative Dimension in Space’.