Simon is a graduate of Cambridge University. He is co-artistic director of TACT (The Actors’ Company Theatre) in New York, and a member of the Advisory Board of NATF (National Audio Theatre Festivals). Simon made his Theatre debut at the Bloomsbury Theatre in London in 1974 and has gone on to gain extensive Theatre credits on both sides of the Atlantic
| 1997 | THE COCKTAIL PARTY | Alexander McColgie Gibbs | Philip Franks | Kings Theatre, Edinburgh Festival | |
| 1982 | THE HARD SHOULDER | David | Nancy Meckler | Hampstead Theatre | |
| 1981 | DESIGN FOR LIVING | Otto | Michael Attenborough | Place Theatre, Watford | |
| 1978 | THE MILLIONAIRESS | Adrian Blenderbland | Michael Lindsay-Hogg | Haymarket Theatre | |
| 1977 | CANDIDA | Lexy | Michael Blakemore | Albery Theatre | |
| 1976/8 | PRIVATES ON PARADE | Eric Young-Love | Michael Blakemore | Royal Shakespeare Company | |
| 1976 | WILD OATES | Zachariah | Clifford Williams | Royal Shakespeare Company | |
| 1975 | THE CLANDESTINE MARRIAGE | Brush | Ian McKellen | Savoy Theatre |
| 1999/2000 | WAITING IN THE WINGS | Perry Lascoe | Michael Langham | For this he was nominated for the Outer Critics Circle Award for Best Featured Actor in a Play | |
| 1999 | RING ROUND THE MOON | Romainville | Gerald Guttierez | Lincoln Centre Theater | |
| 1998 | THE HERBAL BED | Barnabas Goche | Michael Attenborough | Eugene O’Neill Theater | |
| 1995 | SCHOOL FOR SCANDAL | Joseph Surface | Gerald Friedman | Lyceum Theater | |
| 1992 | THE REAL INSPECTOR HOUND | Moon | Gloria Muzio | Roundabout Theater | |
| 1992 | HAMLET (Tom Stoppard’s 15 minute version) | Hamlet | Gloria Muzio | Roundabout Theater | |
| 1991/2 | PRIVATE LIVES (with Joan Collins) | Elliot Chase | Arvin Brown | Broadhurst Theater | |
| 1986 | BENEFACTORS | Colin | Michael Blakemore | ||
| 1984/5 | THE REAL THING | Max | Mike Nichols | Plymouth Theater |
| 1991/2 | PRIVATE LIVES (with Joan Collins) | Elliot Chase | Arvin Brown | ||
| 1984 | AREN’T WE ALL | Willie Tatham | Clifford Williams |
| 2005 | HOME | Jack | Scott Alan Evans | The Actors Company Theatre | |
| 2002 | LONG ISLAND SOUND | Evan Lorrimer | Scott Alan Evans | ATA | |
| 2000 | PASSION PLAY | James Croxley | Ellie Renfield | Minetta Lane Theatre | |
| 1998 | YOU NEVER CAN TELL | Fergus Crampton | Nicholas Martin | Roundabout Theater | |
| 1997 | THE QUICK CHANGE ROOM | Sergei Sergeivitch Tarpin | Orson Bean | Intar Theater | |
| 1995 | CALL ME MADAM | Sebastian Sebastian | Charles Repole | Encores! City Center | |
| 1989 | PRIVATES ON PARADE | Major Flack | Larry Carpenter | Roundabout Theater | For this he was nominated for the Drama Desk Award for Best Featured Actor |
| 1988 | WOMAN IN MIND | Dr. Bill Windsor | Lynne Meadow | Manhattan Theatre Club | |
| 1984 | TERRA NOVA | Dr. Wilson | Gerald Guttierez | Playwrights’ Horizon |
| 2005 | DAVID COPPERFIELD | Mr. Micawber | Anne Keefe & Joanne Woodward | Westport Country Playhouse | |
| 2005 | DEAR BRUTUS | Matey | Gregory Boyd | Westport Country Playhouse Connecticut | |
| 2004 | MY FAIR LADY | Henry Higgins | Gary Griffin | McCarter Princeton & Hartford Stage | |
| 2002 | WHERE’S CHARLEY? | Sir Francis Chesney | Nicholas Martin | Williamstown Theatre Festival | |
| 1996 | THE ROYAL FAMILY | Herbert Dean | Nicholas Martin | Williamstown Theatre Festival | |
| 1993 | MY FAIR LADY | Henry Higgins | Larry Carpenter | Papermill Playhouse | |
| 1993 | DON’T DRESS FOR DINNER | Bernard | Pamela Hunt | Papermill Playhouse | |
| 1986 | MY FAIR LADY | Henry Higgins | Michael Montel | Fisher Theater, Detroit | For this he won the Detroit Free Press Award for Best Actor |
| 2005 | BETRAYAL | Robert | Wang Meiyin | Singapore Repertory Theatre |
| 2005 | GRIFFIN & PHOENIX | Professor Aynsley | Ed Stone | Gold Circle Films | |
| 2004 | THE HITCHHIKER’S GUIDE TO THE GALAXY | Ghostly Figure | Garth Jennings | Mostly Harmless Ltd | |
| 2002 | PARTY MONSTER | Antony | Fenton Bailey | ||
| 1996 | THE DEVIL’S OWN | Harry Sloane | Alan Pakula | Columbia | |
| 1995 | 12 MONKEYS | The Zoologist | Terry Gilliam | Universal | |
| 1994 | MIRACLE ON 34th STREET | Mr. Shellhammer | Les Mayfield | 20th Century Fox | |
| 1992 | FOR LOVE OR MONEY | Albert the Concierge | Barry Sonnenfeld | Imagine Films | |
| 1990 | AMERICAN FRIENDS | Anderson | Tristram Powell | British Screen/BBC | |
| 1990 | GREEN CARD | The Guest | Peter Weir | Buena Vista | |
| 1983 | BRAZIL | Arresting Office Quigley | Terry Gilliam | Universal | |
| 1983 | CLUB PARADISE | Toby Prooth | Harold Ramis | Warner Bros | |
| 1982 | PRIVATES ON PARADE | Eric Young-Love | Michael Blakemore | Orion Classics | |
| 1982 | MONTY PYTHON’S MEANING OF LIFE | Chadwick/Jeremy | Terry Jones | Universal | |
| 1982 | AND NOTHING BUT THE TRUTH aka GYRO CITY (UK release) | Henderson | Karl Francis | Lorimar Films | |
| 1979 | REDS | Times Correspondent | Warren Beatty | Paramount | |
| 1979 | SIR HENRY AT RAWLINSON END | Joachim | Steve Roberts | Charisma Films | |
| 2002 | LEWIS & FREUD: A QUESTION OF GOD | C.S. Lewis | Catherine Tatge | PBS Series | |
| 2002 | CAMBRIDGE SPIES | Sir Michael Bodle | Tim Fywell | BBC | |
| 2002 | OZ | Judge Mason Koesler | HBO (recurring character) | ||
| 2000 | LAW & ORDER: SPECIAL VICTIMS UNIT | Darien Marshall | NBC | ||
| 2000 | BENJAMIN FRANKLIN | Thomas Penn | PBS Series | ||
| 1997 | PARAMOUR | Professor Elliott Dexter | AMC (series regular) | ||
| 1997 | ONE LIFE TO LIVE | Sir Guy Armitage | ABC (recurring character) | ||
| 1996 | REMEMBER WENN | Ted. E. Peck | AMC (guest lead) | ||
| 1994 | THE COSBY MYSTERIES | Winston Murdoch | NBC (guest lead) | ||
| 1994 | LIBERTY! THE AMERICAN REVOLUTION | Ambrose Searle | PBS Series | ||
| 1991 | SHRINKS | Jack Cavendish | Thames TV | ||
| 1988 | TATTINGER’S | Norman | NBC (series regular) | ||
| 1987 | MURDER, SHE WROTE | Barnaby Friar | CBS (guest lead) | ||
| 1987 | KING OF THE BUILDING | Jamieson | CBS (series regular) | ||
| 1987 | NEWHART | Dr. Miles Randall | CBS (guest lead) | ||
| 1986 | CLAWS | Eric | BBC TV MOW | ||
| 1985 | BLACK ADDER II | Sir Walter Raleigh | John Lloyd (producer) | BBC | |
| 1983 | THE PRICE | Lansbury | PBS | ||
| 1983 | THE NEWS IS THE NEWS | Co-Host/Presenter | NBC (series regular) | ||
| 1983 | HART TO HART | Calvin | ABC (guest lead) | ||
| 1981 | MUCK & BRASS | Basil Bastedes | ITV | ||
| 1980 | BRIDESHEAD REVISITED | Bridey | Charles Sturridge | Granada | |
| 1980 | THE HITCH-HIKER’S GUIDE TO THE GALAXY | Arthur Dent | Alan J.W. Bell | BBC | |
| 1976 | ROCK FOLLIES | Juan les Pins | Thames TV |
| 2009 | THE ADVENTURES OF SEXTON BLAKE | Sexton Blake | Dirk Maggs | BBC R2 | |
| 2008 | THE KING OF COMEDY: GEOFFREY PERKINS | Interviewee | Simon Elmes | BBC R4 | |
| 2007 | 28 ACTS IN 28 MINUTES | Participant | Ed Morrish | BBC R4 | |
| 2006 | QUOTE UNQUOTE | Panellist | Tilusha Ghelani | BBC R4 | |
| 2005 | THE CLUB OF QUEER TRADES | Montmorency | Simon Nicholls | BBC R4 | |
| 2004 | THE O. HENRY STORIES | O. Henry | Philip Glassborow | USA Radio | |
| 1978/2005 | THE HITCHHIKER’S GUIDE TO THE GALAXY | Arthur Dent | Simon Brett/ Geoffrey Perkins/ Dirk Maggs | BBC R4 | |
| 2002 | LITTLE WOMEN | Mr. March | Philip Glassborow | USA Radio | |
| 2000 | THE VISITOR | Edward Fitzgerald | BBC R4 | ||
| 2000 | TALES FROM THE CRYPT | Brian Smith | USA Networks/ Sci-Fi Channel | ||
| 2000 | ASPECTS OF OSCAR | Oscar Wilde | Barry Day | Sound Shadows | |
| 2000 | TOO DEAD TO SWING | Morris | Hal Glatzer | Audioplaywrights Inc. | |
| 1998 | TALK OF NEW YORK | Series Host | Jonathan James-Moore | BBC R4 | |
| 1990 | THE NORMAN CONQUESTS | Reg | Gordon House | BBC World Service |
Simon’s audio cassettes are numerous. He was recently awarded two notable mentions as: a Golden Voice by AudioFile Magazine (Dec.04-Jan.05) and as Narrator of the Year by Publishers Weekly (3.1.05).