Shepherd attended Roundhay School in Leeds and then studied fine art at Kings College, Newcastle. During his time in Newcastle he was an amateur actor with the People's Theatre. After gaining a BA he went on to study acting, first at the Central School of Speech and Drama and then as a student founder of the Drama Centre London.
He worked at the Royal Court Theatre from 1965 to 1969, making his first appearance on the London stage as an Officer of Dragoons in Serjeant Musgrave's Dance. In July 1967 he played Arnold Middleton in David Storey's The Restoration of Arnold Middleton, which transferred to the Criterion Theatre, a performance for which he received the Plays and Players London Critics' Award as most promising actor of the year.
During the 1970s he appeared in many television dramas, including several appearances in the series Budgie (1971–72). In Ready When You Are, Mr McGill (1976) by Jack Rosenthal he played a television director struggling to maintain his composure during a doomed location shoot, and in Trevor Griffiths's Thames TV series Bill Brand (also 1976) a radical Labour MP. Both performances gained Shepherd Royal Television Society (RTS) Awards. He appeared as Renfield in Count Dracula (1977), with Louis Jourdan in the title role.
Shepherd also spent the decade running a drama studio in Kentish Town, north London along with fellow actor Richard Wilson, and during that time became interested in playwriting. He devised several plays for the theatre including The Sleep of Reason, Real Time, Clapperclaw and Half Moon.
In 1972 he was a founding member, along with Ian McKellen and Edward Petherbridge, of the democratically run Actors' Company, playing Vasques in 'Tis Pity She's a Whore, Inspector of Police in Ruling the Roost (Edinburgh Festival and tour) and Okano in The Three Arrows at the Arts, Cambridge in October 1972. In December 1972 he played Ben in David Mercer's Let's Murder Vivaldi at The King's Head Theatre, and in January 1973 took the title role in Dracula at the Bush Theatre, also collaborating in the writing.
From 1977 to 1985 he was a member of Bill Bryden's Cottesloe Theatre Company at the National Theatre, playing Teach in American Buffalo, Judas in The Passion, Boamer in Lark Rise, Thomas Clarkeson in The World Turned Upside Down, Smitty in The Long Voyage Home, The Correspondent in Dispatches and Hickey in The Iceman Cometh. Shepherd originated the stage role of Richard Roma in Glengarry Glen Ross at the Cottesloe in 1983, for which he received a Society of West End Theatre award (later known as the Laurence Olivier Awards) as Actor of the Year in a New Play.
His first written work for the stage was In Lambeth, an imaginary conversation about revolution between the poet and artist William Blake, his wife Catherine and Thomas Paine, author of The Rights of Man. He first directed it at the Partisan Theatre in July 1989 before its transfer to the Donmar Warehouse, winning the 1989 Time Out Awards for Best Directing and Best Writing.
Shepherd's work in television during the 1980s and 1990s included "Blind Justice", a miniseries by Peter Flannery, and culminated in his acclaimed role as the eponymous Detective Superintendent Charles Wycliffe in the HTV television series Wycliffe from 1993 to 1998. He appeared as Butler the Butler in the 1996 television miniseries Over Here.
As a theatre director he has staged several productions at the Shakespeare's Globe, including his lively 'Prologue Production' of The Two Gentlemen of Verona starring Mark Rylance as Proteus, which opened the Globe to the theatregoing public in August 1996, a year before the formal opening Gala. In 1998 at the Globe he played a sad Antonio in Richard Olivier's production of The Merchant of Venice.
Shepherd's epic drama about the Chartist movement, Holding Fire! was commissioned by the Shakespeare's Globe Theatre as part of its Renaissance and Revolution season, and was first staged there by Mark Rosenblatt in August 2007.
He played the part of the Father in Rupert Goold's production of Six Characters in Search of an Author in 2009, the Doctor in The Master Builder at the Almeida, and Melchior, one of the Magi, in the four-part TV drama The Nativity, broadcast on BBC One in December 2010. 2013 he played Harry in "Home" by David Storey at the Arcola Theatre and Joe in the BBC TV series "The Politician's Husband". In 2014 Serebryakov in "Uncle Vanya at the St James Theatre. Also in 2014 he toured in 3 Ghost Stories for Middleground Theatre Company.
His interest in community theatre led to adaptations of "Dorian Gray" and of Hardy's "Under the Greenwood Tree" for the Players Collective in Lewes. His version of "Under the Greenwood Tree" was performed by the Hardy Players in Dorchester in Dec 2016.
Plays include:The Incredible Journey of Sir Francis Younghusband (Royal Court Upstairs)
The Sleep of Reason (Traverse Theatre, Edinburgh) 1973
The White Devil - Old Vic - 1976
Clapperclaw (BBC Two) 1981
Real Time (directed and devised with the Joint Stock Theatre Company) 1982
Revelations (Bridge Lane, London) 1983s.
In Lambeth (Partisan Theatre and Donmar Warehouse) 1989. Published by Methuen.
Comic Cuts (Derby Playhouse, Salisbury Theatre and Lyric Studio, Hammersmith) 1995
Chasing the Moment (BAC1 London) 1995, (revived Arcola, Dalston) 2007. Published by First Write
Half Moon (Southwark Playhouse) 1998
Through a Cloud (Birmingham Rep and Drum, Plymouth) 2004), revived Arcola) 2005. Published by Nick Hern Books.
Man Falling Down: A Mask Play (devised and co-written with Oliver Cotton, Shakespeare's Globe) 2005
Holding Fire! (Shakespeare's Globe) 2007. Published by Nick Hern Books
Co-wrote with Keith Dewhurst "Impossible Plays", an account of his years in Bill Bryden's Cottesloe Company at the National Theatre. Published by Methuen.
His two recently completed plays are "Against the Tide", about William Morris, and "The Valley of the Shadow" about the First World War.All Neat in Black Stockings (1969)
The Virgin Soldiers (1969)
The Bed Sitting Room (1969)
The Last Valley (1970)
Something to Hide (1972)
Ready When You Are, Mr. McGill (TV) (1976)
Count Dracula (TV) (1977)
The Devil's Crown (TV) (1978)
Scoop (TV) (1987)
Body Contact (1987)
Escape from Sobibor (1987)
Lights and Shadows (1988)
The Party (TV) (1988)
Ball Trap on the Cote Sauvage (1989)
Murderers Among Us: The Simon Wiesenthal Story (1989)
The Big Man (1990)
Shoot to Kill (1990)
The Object of Beauty (1991)
Blue Ice (1992)
No Escape (1994)
Over Here (1996)
The Scarlet Tunic (1998)
Charlotte Gray (2001)
The Martins (2001)
A Cock and Bull Story (Tristram Shandy) (2005)
All About George as Gordon Kinsey (2005)
The Golden Compass (2007)
God on Trial (TV) (2008)
The Nativity (TV) (2010)
Thorne: Sleepyhead (TV) (2010)
The Politician's Husband (TV) (2013)
Midsomer Murders (TV) (2015) episode 17.2 "Murder by Magic" - Magnus Soane