- Thorley Walters - Dr. Ledworth
- Dinsdale Landen - Matthew Earp
- Malcolm Terris - Detective Superintendent
- Andrea Allan - Janet Cunningham
- Patrick Tull - Terry
- David Daker - Charlie Draper
- Alan Browning - Supt. Brook
- Ray Smith - Ben Tamplin
- Diana Weston - Helen Wiles
- James Cossins - Kellet
- Robert Dorning - Dr. Arthur Sammers
- Patricia Kneale - Mrs. Mansell
- Tom Conti - Bruno Varella
- Jan Francis - Gillie Randall
- Barbara Feldon - Jenny Frifth
- Dennis Waterman - Frank
- Sydney Tafler - Sam Meadows
- Kim Darby - Helen
- Tony Anholt - Johnny Baxter
- Glynn Edwards - Lob
- Robert Beatty - Dan Summers
- Bob Holness - Announcer (voice)
- Molly Weir - Miss Pendy
- Edward Hardwicke - Gifford
- Stephen Rea - Arden Buckley
- Geoffrey Whitehead - Keston
- Gerald Sim - Peterson
- Derek Fowlds - Dicky
- Helen Mirren - Stella McKenzie
- Richard Vernon - George Cornfield
- David Warbeck - Robert Miller
- Moira Redmond - Janice Main
- George Chakiris - Robert Stone
- Patrick Magee - Prof. Marcus Carnaby
- Cec Linder - Edgar Harrow
- Edd Byrnes - Eddie Vallance
- Alister Williamson - Barkly
- Joanna Dunham - Penny Burns
- Zena Walker - Betty Drew
- Stuart Wilson - Max Burns
- Stuart Damon - Hal Bridie
- Mark Wing-Davey - Cater
- Colin McCormack - Peter
- Catherine Schell - Julie
- James Maxwell - Carter
- Jennifer Daniel - Liz
- Arnold Ridley - 1st Old Man
- Gerald Harper - Greg Miles
- Peter Cellier - Col. Wright
- John Le Mesurier - Stubbs
- Paul Burke - Brad Hunter
- Tim Wylton - Forbes
- Ralph Bates - Michael Spencer
- Ivor Roberts - Doctor
- Gemma Jones - Helen Curry
- Bob Hoskins - Sammy Draper
- Josephine Tewson - Yvonne
- Leigh Lawson - Larry Turner
- Angharad Rees - Stella Mason
- Faith Brook - Betty Cornfield
- Nyree Dawn Porter - Laura
- Anthony Steel - Mr. Burton
- Jenny Agutter - Dominie Lanceford
- Derek Bond - Maycroft
- Gilly Flower - Miss Cardiff
- Lynda Day George - Cathy More
- James Smillie - Bob Malory
- Ed Bishop - Carson
- Don Henderson - Boz Bostyne
- Trevor Baxter - Winters
- Jim Norton - The Man
- Ian Hendry - Terry Spelling / Bob Spelling
- Jeremy Bulloch - Tom Manners
- Denholm Elliott - Dr. Frank Henson
- Michael Byrne - Richard Lovell
- Holly Palance - Susie Kay
- Suzan Farmer - Gilly
- John Challis - Peter
- Judy Carne - Gillian Pemberton
- Diane Cilento - Clara
- Peter Bowles - Supt. Lucas
- Richard Johnson - George Drew
- Basil Henson - Charles Merrow
- Dallas Adams - Douglas Sadler
- Beth Morris - Sally Kirby
- Sydney Bromley - Seth
- Bruce Boa - Hanley
- Carroll Baker - Sandy Marshall
- Keith Baxter - Tony Risanti
- Norman Eshley - Arthur Page
- Freddie Jones - Arnold Tully
- Richard O'Callaghan - George Bailey
- Leslie Schofield - Moore
- John Hallam - Roscoe
- Dudley Sutton - Gadder
- Christopher Benjamin - Medical Officer
- Peter Jeffrey - Dexter
- Ken Jones - Sam
- Windsor Davies - Detective Moore
- Jean Kent - Mrs. Garrick
- Laurence Payne - John Jacey
- Christopher George - Bernard Peel
- Anton Diffring - Jonathan Lanceford
- Michael Gwynn - Oliver Mason
- Sheila Fearn - Prudence Claire
- Charles Gray - Hilary Vance
- Roddy McMillan - Inspector Fillory
- Donal McCann - Jeff Holt
- Andrea Marcovicci - Ruth Harrow
- Petra Markham - Helga Muller
- Ingrid Pitt - Ilse
- Sue Holderness - Betty
- Maureen Lipman - Liz Morris
- Bryan Marshall - Dr. Bruce Nelson
- Polly Bergen - Suzy Hunter
- Darleen Carr - Katey Summers
- Ian Bannen - Doonan
- Ian Bannen - Frank Dean
- Richard Aylen - Insp. Miles
- James Villiers - Paul
- Cavan Kendall - Tim Foster
- David Jackson - Martin
- John Abineri - Insp. Buff
- Brian Blessed - Det Sgt George Briggs
- Mary Wimbush - Mrs. Bradley
- Scott Forbes - Mr. Patrick
- Oliver Tobias - Alan Smerdon
- David Horovitch - Tredgett
- Philip Stone - Burton
- Ronald Radd - Supt. Terson
- Edward de Souza - Tony Mansell
- Christopher Ellison - Denver
- Russell Hunter - Old Fred
- Hayley Mills - Samantha Miller
- Tony Selby - Mark
- John Nolan - Marty Fuller
- Arthur English - Freddy
- Jennie Linden - Sister Mary / Penny Stacey
- Patrick O'Neal - Michael Lane
- Patrick Allen - Richard Main
- Michael Kitchen - George Newton
- Michael Kitchen - Ian
- David Lodge - Bradley
- Diana Dors - Bessy Morne
- Pamela Franklin - Abby Stevens
- Pamela Franklin - Nicola Stevens
- Jacki Piper - Bride
- Max Wall - Jorg Kesselheim / George Thibedon
- Joanna Pettet - Sylvia Dee
- Joanna Pettet - Jody Baxter
- Oliver MacGreevy - Henry
- Rhoda Lewis - Emma Patrick
- James Grout - Supt. Cramer
- Elaine Donnelly - Esme
- Donna Mills - Helen Cook
- Donna Mills - Patty Heron
- Donna Mills - Chrissie Morton
- Sinéad Cusack - Sally
- T. P. McKenna - Jack Hardisty
- T. P. McKenna - Frampton
- Christopher Malcolm - Hank
- Ronald Leigh-Hunt - Giles Turner
- Gabrielle Drake - Tracy
- Paul Angelis - Terry Cleeves
- Anthony Valentine - Garard
- Linda Thorson - Toni Tanner
- Norman Rodway - Peter Ingram
- John Carson - Ray Burns
- John Carson - Arthur Lewis
- Martin Benson - Spiros Lemke
- Neville Phillips - Bar Waiter
- Hans Meyer - Karl Vorster
- Bernard Holley - Paul Eastman
- Jacqueline Tong - Sally
- Gary Collins - Dave Adams
- Gary Collins - Howard Heston
- Gary Collins - Hugh Briant
- George Maharis - Mark Fields
- Robert Lang - The Man
- Gary Watson - Inspector Rush
- Julia Breck - Samantha
- Patrick Troughton - Lyall
- Geoffrey Chater - Graham
- Geoffrey Chater - Sir Peter Hastings
- Hazel McBride - Nurse
- Eric Flynn - Michael Slattery
- Judy Geeson - Helen Marlow
- John Turner - Bart
- John Nightingale - Steve Kerroway
- Stephen Greif - Ben Kroom
- Stephen Greif - Enrico
- Ronald Lacey - Bartlett
- Edward Judd - Bill Lewis
- Edward Judd - Charles Burns
- William Marlowe - Jeffries
- John Bailey - Kemp
- Alison Glennie - Annabella Tully
- David Gwillim - Henry Venner
- Susan Flannery - Anna Cartell
- Nigel Havers - Ludovic Bates
- Julian Glover - Gifford
- Claire Nielson - Hilary
- William Job - Trasker
- Patrick Jordan - Inspector Turner
- Patricia Donahue - Elizabeth Lane
- Robert Morris - Freddy Green
- Colette O'Neil - Alice Lewis
- John Arnatt - Mr. Robinson
- Derek Francis - Shelby Grafton
- Derek Francis - Sam
- James Greene - Constable Breck
- James Greene - Policeman
- Harold Bennett - Blind Man
- Harold Bennett - 2nd Old Man
- Gayle Hunnicutt - Suzy Buckley
- Bradford Dillman - Gary Stevens
- Bradford Dillman - Stan Kay
- Richard Todd - George Tulliver
- Tony Steedman - Detective Quilly
- Michael Jayston - Mark Walker
- Michael Jayston - Roger Masters
- Julie Sommars - Ann Rogers
- Wendy Williams - Mrs. Fuller
- Ray Marioni - Waiter
- Ray Marioni - Croupier
- Alexandra Hay - Tessa Nelson
- John Boswall - Old Man
- Alun Armstrong - Mike
- Ian Gelder - Small
- Susan Hampshire - Sally
- Anthony Pedley - Charley Spencer
- Keith Barron - Charley Masters
- Gillian McCutcheon - Janice Freeman
- Carol Lynley - Suzy Martin
- Robert Powell - Paul Tanner
- Robert Powell - Rook
- Arthur White - Charley Wilson
- Gerald James - Barnes
- Michael Culver - Simon Burns
- John Cater - Murchison
- Stephen Yardley - Tosher
- Jenny Laird - Nan
- Robyn Millan - Kathy
- Peter Vaughan - Anderson
- Christopher Cazenove - Sunny Garrick
- Jeremy Brett - Peter Tower
- Jimmy Gardner - Caretaker
- Penelope Horner - Clarissa Briant
- John Flanagan - Wilson
- John Flanagan - Michael Player
- Jonathan Elsom - John Stratford
- Ronald Mayer - Dr. Lambert
- Barrie Fletcher - Detective Sergeant Sullivan
- Richard Beaumont - Howard as a child
- Georgine Anderson - Jane
- Michael Stainton - Policeman (uncredited)
- Michael Stainton - Brent
- Laurie Johnson
Alun Armstrong interpreta a Mike en la serie.
Peter Vaughan hace el papel de Anderson.
Ronald Lacey interpreta a Bartlett en la serie.
Julian Glover hace el papel de Gifford.
Thorley Walters interpreta a Dr. Ledworth en la serie.
Dinsdale Landen hace el papel de Matthew Earp.
Malcolm Terris interpreta a Detective Superintendent en la serie.
Andrea Allan hace el papel de Janet Cunningham.
Patrick Tull interpreta a Terry en la serie.
David Daker interpreta a Charlie Draper en la serie.
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