As Ian's condition worsens, the Doctor still searces for a cure to the mysterious illness. However, the Doctor's efforts are undermined by the Sensorite City Administrator.

Nina Thomas played Thalira in the Doctor Who serial The Monster of Peladon.

Also appeared in Doctors, London, Wilderness, The Upper Hand, Boon, Brookside, The Last Song, The History of Mr. Polly, Thomas and Sarah, Within These Walls, Just William, Rooms, The Sweeney, BBC Play of the Month, The Prince and the Paupe, The Dancing Years, Comedy Premiere, Crown Court, Flame, Father Brown, ITV Sunday Night Drama, Village Hall, Dead Cert, The Fortunes of Nigel, Public Eye, ITV Sunday Night Theatre

Oscar James is a Trinidadian actor, who is based in the United Kingdom. 

He has had a long and varied career, but is best known for appearing on British television, in particular the BBC soap opera EastEnders, where he played original character, Tony Carpenter, for over two years.

William Marlowe was a British theatre, television and film actor.

He appeared in Doctor Who as Harry Mailer in the 1971 story The Mind of Evil and as Lester in the 1975 story Revenge of the Cybermen 

He was cast as Sir Guy of Gisbourne in The Legend of Robin Hood (1975) and appeared in A Family at War and The Gentle Touch 

Other guest star roles include Barlow (1975), Breakaway (1980), Callan (1972) and Catch Hand (1964). Later he played Chief Supt. Thomas in The Chief (1990).

He was married to the daughter of actor Peter Bathurst, and later to actress Catherine Schell between 1968 and 1977, before marrying Roger Delgado's widow Kismet in 1979.

Kevin Stoney was an English actor, best known for his television roles.

He is well remembered by fans of  Doctor Who for his roles in three serials � Mavic Chen in The Daleks' Master Plan (1965), Tobias Vaughnin The Invasion (1968) and Tyrum in Revenge of the Cybermen (1975).  

During World War II, Stoney served with the Royal Air Force.

Stoney also appeared in two episodes of another science fiction series, Blake's 7, playing Councillor Joban in the episode Hostage and Ardus in the episode Animals.

He is also noted for his role as the astrologer Thrasyllus in the 1976 BBC adaptation of I, Claudius, a role he had earlier played in Granada Television's 1969 series The Caesars.

Other credits include: The Adventures of Robin Hood, The Saint, Danger Man, The Avengers, Dr. Finlay's Casebook, The Prisoner, Softly, Softly, Man in a Suitcase, The Troubleshooters, Doomwatch,Freewheelers, Z-Cars, The Tomorrow People, Ace of Wands, Special Branch, The Onedin Line, Fall of Eagles, Space: 1999, The New Avengers, Quatermass, Bergerac, All Creatures Great and Small, The Bill and in the highest rated episode of Inspector Morse.

In 1985, it was reported in the Doctor Who fan magazine, DWB, that Kevin Stoney had died at the age of 64, but in 1987, Stoney made an appearance at a Doctor Who convention to prove he was very much alive, to the shock of the fans.

Kevin Stoney died in Chiswick, after a long battle with skin cancer.

Cyril Luckham was a British film, television and theatre actor.

Luckham played the White Guardian in Doctor Who. He appeared in The Ribos Operation, the first serial in The Key to Time season, and Enlightenment. 

He appeared in an episode of Randall and Hopkirk (Deceased) (1969), as the villain.He appeared the 1978 TV series based on The Famous Five books by Enid Blyton, as the evil psychic Edward Drexel in the 1979 supernatural thriller series The Omega Factor, and as the equitable Chair of the school board of Bamfylde in the 1980 Andrew Davies adaptation of To Serve Them All My Days. He also portrayed Archbishop Thomas Cranmer in the film adaptation of A Man for All Seasons (1966) and the long-suffering Father O'Hara in Some Mothers Do 'Ave 'Em.

Hywel Bennett  was a Welsh film and television actor who was best known for his recurring title role as James Shelley in the television sitcom Shelley from 1979 to 1984 and its sequel The Return of Shelley from 1988 to 1992.

He appeared in the 1965 Dalek story, The Chase.

Bennett was born in Garnant, Carmarthenshire, Wales. Brought up in London from an early age, he attended Sunnyhill School, Streatham, Henry Thornton Grammar School, Clapham and the Royal Academy of Dramatic Art.

He appeared in The Sweeney (1976). He starred in The Virgin Soldiers (1969), the film adaptation of Loot (1970) by Joe Orton, Percy (1971) and played the lead role in Shelley (1979-84) and its sequelThe Return of Shelley (1988-92). He was also cast opposite former child star Hayley Mills in several films including The Family Way (1966), Twisted Nerve (1968) and Endless Night (1972).

He played major parts in several Dennis Potter television plays, including Where the Buffalo Roam(1966), Pennies From Heaven (1978), Karaoke (1996), and Cold Lazarus (also 1996). He was also the villainous Mr. Croup in Neil Gaiman's miniseries Neverwhere (1996). His character, Ricki Tarr, was pivotal in the 1979 BBC miniseries based on the John le Carr novel, Tinker, Tailor, Soldier, Spy (1979). He also appeared in Lock, Stock... (2000) as "Deep Throat". Bennett also starred in the four-part 1979 BBC mini series Malice Aforethought from the original novel, written in the 1920s, by Francis Iles.

In 2003, he joined the cast of long running soap opera EastEnders as Jack Dalton, a gangland boss who was introduced into the series as a former adversary of Den Watts (played by Leslie Grantham) whose death he was believed to have ordered in 1989. He first appeared in the series in May 2003 but was written out just two months later when his character was shot dead by Dennis Rickman(Nigel Harman), son of Den Watts; just before his demise, the character revealed that Den had survived the shooting 14 years earlier, and later that year Den returned to the series.

He also appeared as an occasional character, Peter Baxter, on The Bill and was in the first episode of Jam & Jerusalem.

Also, he appeared in the 1986 music video of "Loving You's a Dirty Job But Somebody's Gotta Do It" by Bonnie Tyler and Todd Rundgren. He playbacked the Todd Rundgren vocals. The song can be found on Bonnie's album Secret Dreams and Forbidden Fire.

From 1967-88, Bennett was married to Cathy McGowan, best known as the presenter of the TV rock show Ready Steady Go! in the mid 1960s. They have a daughter, Emma.

Bennett retired in 2007 after being diagnosed with a congenital heart defect.

Robin Phillips played Altos in five episodes of the 1964 story The Keys of Marinus, accompanying the Doctor and his companions in their quest for the Conscience's keys. 

Phillips was born in Haslemere, in 1942. He studied acting at the Bristol Old Vic and went on to appear in many well known TV series including Compact, The Forsyte Saga, The Avengers and The Saint. In 1969 he played the title character in the star studded TV version of Charles Dickens' David Copperfield. 

In 1975 he was hired as artistic director at the Stratford Festival in Canada. He spent six seasons directing many productions starring such actors as Maggie Smith, Richard Monette, Martha Henry, and Brian Bedford, directing 40 productions. He made Canada his home, becoming a Canadian citizen and developing a wide-ranging career in the country, including a period as artistic director at The Grand Theatre in London, Ontario, and as director general of Edmonton's Citadel Theatre. 

Phillips's directing credits included a London production of Long Day's Journey into Night starring Jessica Lange, the Broadway musical Jekyll and Hyde, and a Canadian Opera Company performance of The Marriage of Figaro.

In 1983 he was given an honorary degree by the University of Western Ontario and was named an Officer of the Order of Canada in 2005. He was honoured with a Lifetime Achievement Award at The Governor General's Performing Arts Awards in 2010

David Jackson was a British actor best known for his role as Olag Gan in the first two seasons of Blake's 7 and as Detective Constable Braithwaite in Z-Cars from 1972 to 1978. He was born in Liverpool, Lancashire.

His other TV credits include The Saint, The Avengers, The Sweeney, Lord Peter Wimsey (The Nine Tailors), Space: 1999, Minder (The Smaller They Are), Only Fools and Horses, Wyatt's Watchdogs, Edge of Darkness, Coronation Street and Lovejoy. His film credits include roles in 10 Rillington Place (1971), Unman, Wittering and Zigo (1971), Blood from the Mummy's Tomb (1971), Night Watch (1973), The Big Sleep (1978) and the cult horror film Killer's Moon (1978).

In 2002, he provided his voice talent to the audio drama Sarah Jane Smith: Comeback, part of the Doctor Who audio spin-offs by Big Finish Productions. Jackson was a science-fiction fan throughout his career and was happy to be associated with Blake's 7 years after the series ended.

In 1988 he showed his considerable comic talent in playing the Vicar alongside Brian Wilde in six episodes of the BBC1 sitcom Wyatt's Watchdogs. His great passion was for Victorian theatre and at one stage he produced and starred in a one-man show.

David Jackson died of a heart attack on 25 July 2005, aged 71. He left behind his wife Anne and 19-year-old son Stuart.

Alf Joint was a British movie and television stunt performer, stunt coordinator and arranger.

He was notable for his contributions in numerous films over a 30 year period including: The Heroes of Telemark (1965), Kelly's Heroes (1970), The Omen (1976), A Bridge too Far (1977), Superman (1978), Superman II (1980), Superman IV: The Quest for Peace (1987), Star Wars Episode VI: Return of the Jedi (1983) and the James Bond films Goldfinger (1964) and On Her Majesty's Secret Service (1969). He also had small acting roles in some films.

As a stuntman he specialised in high falls and fight scenes. He doubled for Sean Connery in the film Goldfinger and for Richard Burton and Clint Eastwood in Where Eagles Dare (1968). Memorable appearances include his fight with Connery as the Mexican thug Capungo in Goldfinger. The fight ends with the character's electrocution in a bath when a sunlamp is thrown in by Bond, followed by his famous quip “Shocking…Positively shocking”. Joint also took part in the fight scene on the top of a cable car in Where Eagles Dare and performed a jump from one cable car to another doubling for Richard Burton. On television he appeared in Doctor Who, Dick Turpin, Return to Treasure Island, Danger Man, The Prisoner, The Avengers, Space: 1999, The Adventures of Sherlock Holmes, (for which he plunged 430ft into the Reichenbach Falls doubling for Eric Porter) and London's Burning. He also performed a memorable stunt for aCadbury Milk Tray television commercial in which the hero was seen diving off a cliff into the sea.

Michael Mundell  played Jasko in the Doctor Who story The Invasion of Time.

Other work included Pirates Island, Home and Away, Secret Army, The Professionals, Softly Softly: Task Force, Dixon of Dock Green, Z Cars , Ace of Wands, Straw Dogs, UFO, The Ballad of Tam Lin, Counterstrike, Crossroads, Theatre 625, Coronation Street, The Blood Beast Terror, Maroc 7, Fahrenheit 451