The Sensorites take the Doctor, Susan, Ian and members of the spaceship crew down to the surface of the Sense-Sphere. There the Doctor learns about a previous Earth expedition...

An alien with an aversion to electricity threatens to take planet Earth back into the Dark Ages

Jonjo O'Neill is an actor from Belfast, Northern Ireland. 

He studied at the Guilford School of Acting. Jonjo has recently finished a three year residency with the Royal Shakespeare Company (RSC) ensemble. He is now back with the RSC playing Richard III. 

Actor who appeared in the 1979 story Nightmare of Eden

Michael Pickwoad was a Production Designer who worked on Doctor Who for the Matt Smith and Peter Capaldi eras (2010-2017), and also for the short-lived spin-off series Class.
His first major success was with the film Withnail and I, before working on Jane and the Lost City, The Lonely Passion of Judith Hearne and How to Get Ahead in Advertising. He worked on several TV movies including Hans Christian Andersen: My Life as a Fairy Tale, The Deal, Death in Holy Orders, Wild West, High Heels and Low Lifes, The Sleeper, David Copperfield, The Last of the Blonde Bombshells, Honest, A Rather English Marriage and Cider with Rosie. Work continued with The Old Curiosity Shop, several episodes of the Miss Marple series, the TV movie of Sweeney Todd, The Queen's Sister, and Archangel. Recent work included The Prisoner and Lost in Austen.

His father was the actor William Mervyn.

Martin Lisemore was Production Assistant for 1968 Doctor Who story The Enemy of the World.

He later became a producer responsible for many period drama series and adaptations, including The Woodlanders, The Spoils of Poynton, and adaptations of Sense and Sensibility in 1971 and Emma the following year.

He quickly established himself as a leading producer of classic period drama, often working in partnership with script editor Betty Willingale. He achieved arguably his greatest success with the dramatisations of How Green Was My Valley (1975-76) and I Claudius (1976), the later winning both BAFTA and Emmy awards.

On 3 February 1977, during the production of his next series, Murder Most English, Lisemore was killed in a road accident.

He was maried to Sarah Lisemore, who appeared in The Enemy of the World.

David Graham  is a British character actor and voice artist.

Born in London, after a period in the R.A.F as a Radar Mechanic he trained as an actor in New York but has worked mainly on British television series. 

He was the voices of Parker, Brains, Gordon Tracy, and Kyrano in the original television series of Thunderbirds and its spin-off films Thunderbirds Are GO and Thunderbird 6. He had roles in several other Gerry Anderson productions, including Stingray, Fireball XL5, Four Feather Falls, The Secret Service and Supercar.

Graham appeared in Callan, Timeslip, So Haunt Me, Danger Man, The Saint, Howards' Way, Softly, Softly, Armchair Thriller, Ace of Wands, Justice, The Regiment, The Bill, The Fixer, The Sentimental Agent,Timeslip and The Avengers (in the 1963 episode "Man in the Mirror"). In the "1984" commercial introducing the Apple Macintosh, he played the role of Big Brother.

He has also done puppet voices in two episodes of The Tomorrow People.

He has also done voice roles in anime including the children's TV series Moomin and the film Dominion: Tank Police.

Graham is currently the voice of "Grandpa Pig" in the children's television program Peppa Pig and the voice of Wise Old Elf in Ben and Holly's Little Kingdom.

Colette O'Neil  was a Glasgow-born actress noted for her various roles on British television.

She appeared in the 1983 story Snakedance.

She was a semi-regular cast member of Coronation Street in the mid-1960s as Ruth Winter, and also made frequent guest appearances in series such as Z-Cars, Dixon of Dock Green, Adam Adamant Lives!, No Hiding Place and Softly, Softly.

She was a leading cast member in the drama series The Standard.

More recently, she appeared in Taggart, Lovejoy, Hamish Macbeth, Heartbeat, Peak Practice, Holby City, Monarch of the Glen and Bad Girls.

Ray Lonnen (born in Bournemouth, Hampshire now Dorset) is an English stage and television actor. His most prominent roles include Willie Caine in the cold-war spy drama series The Sandbaggers (1978-80), and also as Harry Brown in the television mini-series Harry's Game (1982).

Lonnen's early television appearances include The Power Game (1966), The Fellows (1967), and Honey Lane (1968). He then had a semi-regular role in the British crime drama series Z Cars between 1972-77, and also appeared the 1973 Doctor Who story Frontier In Space.

Lonnen played one of the leads in the 1978 ITV espionage series The Sandbaggers, in which he played Willie Caine (aka "Sandbagger 1"). The Sandbaggers ran for three series until 1980. Lonnen's next lead role was in the 1982 ITV mini-series Harry's Game, based on the novel by Gerald Seymour. In this, Lonnen played Harry Brown, a British agent sent to Northern Ireland to smoke out an IRA assassin who had slain a cabinet minister. In 1984, Lonnen went on to star in yet another spy-themed drama series, The Brief, in which he played a British barrister who travels to Germany to represent a British soldier accused of spying and treason. Aside from his lead roles, Lonnen also continued to appear in guest roles throughout the 1980s, including episodes of The Gentle Touch, Hammer House of Horror, Tales of the Unexpected, Lovejoy and the French film Mangeuses d'Hommes.

In 1990, Lonnen played Detective Inspector Alex Vale in the ITV detective drama series Yellowthread Street, which was set in Hong Kong. Based on the novels by William Leonard Marshall, the series ran for 13 episodes.

Throughout the 1990s, Lonnen continued to make guest appearances in various television series and even voiced several characters in the children's animated series Budgie the Little Helicopter.

In 2001, he had a recurring role in the ITV police series The Bill. He also appeared in several episodes of the Canadian sci-fi series Starhunter as well as a recurring role in the short-lived revival of the ITV soap-opera Crossroads.

Since the 1960s, Lonnen has performed in a variety of stage roles, including drama, comedy and musicals. His stage credits include Under Milk Wood (as the Narrator), In Praise of Love, Run for Your Wife, Having a Ball, Wonderful Town, Make Me An Offer, Lock Up Your Daughters, Wonderland, Bells Are Ringing, How the Other Half Loves, The Anniversary, A Touch of Danger, Murder by the Book, Same Time Next Year, Misery, Worm's Eye View, Rebecca, Jeffrey Archer's The Perfect Murder and he has played Sky Masterson in Guys and Dolls. He also played Clark Gable in a play about the making of the 1961 film The Misfits, he toured South-East Asia in a production of Catch Me If You Can, and also toured New Zealand in the play Rose.

He was married to the actress Tara Ward.

He died in 2014 after a three year battle against cancer.

_{Biography from the Wikipedia article, licensed under CC-BY-SA}

John Breslin was born in  Glasgow, Scotland, UK 

He had an extensive career in British Television and films. 

He played Alan a Dale in the 1953 TV version of Robin Hood

Derek Pollitt appeared in several Doctor Who stories: as Driver Evans in The Web of Fear, Private Wright in Doctor Who and the Silurians, and A. St. John D. Caldera in Shada.

Also worked on The Onedin Line, Bread, Biography, The Body Stealers, Z Cars, Coronation Street

Roy Purcell was an English actor who appeared in two Doctor Who stories in the early 1970's.

He also appeared in The Collectors, Z Cars and The Troubleshooters.

Hugh Morton played Sir James Gregson in the Doctor Who story The Seeds of Death.

With Bernadette Hodgson as wife Steve, was the first actor to play Francis Durbridge's sleuth Paul Temple in three BBC Radio serials from April 1938 ("Send for Paul Temple") to December 1939 ("News of Paul Temple").

Also worked on Hammer House of Mystery and Suspense, Oxford Blues, Ladykillers, The Life and Times of David Lloyd George, The Professionals, BBC2 Playhouse, Invasion, Why Didn't They Ask Evans?, Suez 1956, House of Caradus, Rebecca, Wodehouse Playhouse, Robin's Nest, The Stud, The Wilde Alliance, The Upchat Line, Philby, Burgess and Maclean, Miss Jones and Son, Jubilee, The New Avengers, Shadows, Against the Crowd, Section spéciale, The Tomorrow People, This Week, The Black Arrow, Good Girl, The Capone Investment, Thriller, The Carnforth Practice, Wessex Tales, The Protectors, Oh, Father!, New Scotland Yard, Six Days of Justice, Pardon My Genie, Man at the Top, Callan, The Brothers, The Shadow of the Tower, The Darwin Adventure, Justice, Bachelor Father, Armchair Theatre, The Rivals of Sherlock Holmes, Paul Temple, The Main Chance, Special Branch, Detective, The Exiles, The Wednesday Play, The Saint, Champion House, ITV Playhouse, Quatermass and the Pit, Z Cars, No Hiding Place, Ways with Words, Mister Misfit, Orlando, Dixon of Dock Green, 199 Park Lane, Zero One, The Man in Room 17, Paris 1900, Master Spy, Swizzlewick, Love Story, The Masque of the Red Death, Sergeant Cork, The Avengers, Boyd Q.C., About Religion, The Plane Makers, Drama 61-67, Three on a Spree, Payroll, Interpol Calling, Bachelor of Hearts, Living It Up, Yesterday's Enemy, Leave It to Todhunter, The Big Money, Uncle Harry, ITV Television Playhouse, Life with the Lyons, Rogue's Yarn