In 1968, he and his older brother, actor Jeremy Sinden, were part of the "Na-Na" chorus on "Hey Jude" by the Beatles.

[5] In 1998, he resumed his independent career as Marc Sinden Productions and produced and co-directed Shakespeare's Villains (Haymarket) with Steven Berkoff, which was nominated for a Society of London Theatre Laurence Olivier Award for Best Entertainment.

[8] Other productions include The Glee Club (Duchess) following its transfer from the Bush Theatre; Seven Deadly Sins Four Deadly Sinners, which he directed and also co-wrote with Carry On... writer Norman Hudis, which is still touring internationally;[9] Asking For Trouble with Sheridan Morley; Sex Wars with Louise Jameson and Straker Sings Brel directed by Mel Smith.

[10] He inaugurated the British Theatre Season, Monaco, bringing English-language theatrical shows to the Théâtre Princesse Grace in Monte Carlo.

[13] He is a producer with his former wife Jo Gilbert and director of the 40-part documentary series Great West End Theatres and was the producer of the DVD release An Evening with... Sir Donald Sinden, filmed at Pinewood Studios and Steven Berkoff's East, filmed in front of a live audience at the Vaudeville Theatre, London in 1999.

[15] In August 1998, Sinden was producing a documentary at Vimy Ridge in Arras, northern France about the First World War underground mines (as mentioned in the Sebastian Faulks novel Birdsong) when Lt-Col Mike Watkins, the Head of Explosive Ordnance Disposal and the British Army's leading bomb disposal expert[16] who was in charge of the decommissioning of the huge bombs (including one of 6,500 lb) in the 20-mile subterranean complex, was killed in an accident underground.

"[21][22][23] In their review of the first 10 episodes of the series, the British Theatre Guide said "This film is as close as one can get to standing on the stage taking an ovation.

"[24] The Daily Telegraph review stated that the "lovely documentary series is made by the director Marc Sinden.

[4] A season at the Chichester Festival Theatre included 'Stephen Undershaft' in George Bernard Shaw's Major Barbara with Donald Sinden, directed by Christopher Morahan and as assistant director, Sam Mendes; at the Gaiety Theatre, Dublin, 'Broadbent' in Shaw's rarely seen John Bull's Other Island with Cyril Cusack, directed by Joe Dowling; 'Cassius' in a national tour of Julius Caesar for the New Shakespeare Company[31] and a 12-month national tour of Noël Coward's Private Lives with Gemma Craven.

with Tom Selleck and as Martyn Price in the BAFTA and Emmy award-winning The Politician's Wife with Trevor Eve and Juliet Stevenson.

He has appeared in Judge John Deed; the series Island set on Jersey and has also had roles in the BBC TV drama series' Century Falls and Country Boy; Against All Odds – The Promise with Roy Marsden;[36] Never the Twain; Bergerac; Peter Tinniswood's Home Front with Brenda Bruce; Barry Morse presents Strange But True; Rumpole of the Bailey with Leo McKern; Emmerdale; If You Go Down in the Woods Today with Eric Sykes; Desmond Elliott in the original series of Crossroads; Joss Melford, opposite Lindsay Duncan in the episode Deadlier Than the Male, in Dick Turpin with Richard O'Sullivan; All at No 20 with Maureen Lipman; Shoestring with Trevor Eve and Wolf to the Slaughter (the first of the Ruth Rendell/Inspector Wexford TV adaptations).

[2] Investigative journalist James Montague, writing in the July 2014 issue of Esquire magazine, claimed that Sinden spied for the British Government's Secret Intelligence Service (MI6) during the filming of Clash of Loyalties in Iraq, after being made "an offer he couldn't refuse, appealing to his duty and his pride in Queen and Country."

[46] He is an atheist and secularist, a Fellow of the Zoological Society, a Liveryman of the Worshipful Company of Innholders and was awarded the Freedom of the City of London by the Lord Mayor Sir Kenneth Cork.