Sidney was born in Balham, south London, only a short walk from Tooting Common, where Common People was filmed. He has enjoyed a long and varied career working with many of the UK's most prestigious theatre companies. Some of the highlights include seasons at the RSC with Directors John Barton, Nicholas Kent, and Terry Hands, productions of "Macbeth", and "The Queen and I", for Out Of Joint, directed by Max Stafford-Clark, and Fred D'Aguiar's, "A Jamaican Airman Foresees his Death", at the Royal Court Theatre.
His numerous TV appearances include many popular UK dramas and comedies including both "French and Saunders" and "Absolutely Fabulous", "Jonathan Creek", and "Casualty". In films, he has worked with Canadian auteur Atom Agoyan on "Felicia's Journe"y starring Bob Hoskins, "Boogie Woogie", starring Gillian Anderson and Danny Huston, and and most recently "The Great Ghost Rescue", starring Kevin McKidd.