His serious and comedic film work included roles in The Crying Game, Peter's Friends and How to Get Ahead in Advertising.

[1] In April 2019 Slattery revealed that he had been repeatedly sexually abused by a priest at the age of eight, but had never told his parents; he believed the event contributed to his unstable character later in life.

[2][3] He was educated at Gunnersbury Boys' School in west London and won a scholarship to read Modern and Medieval Languages at Trinity Hall, Cambridge, specialising in French literature and Spanish poetry.

[4] At the University of Cambridge, Slattery discovered a love of the theatre, taking delight in making people laugh.

[5] Other members at that time included Hugh Laurie, Emma Thompson, Sandi Toksvig, Jan Ravens and Richard Vranch.

[6] In 1981 Slattery, Fry, Laurie, Thompson and Toksvig won the inaugural Perrier Award for their revue The Cellar Tapes.

[9] Slattery first broke into television as a regular performer on Chris Tarrant's follow up to O.T.T., Saturday Stayback (1983),[10] while also appearing for children in Behind the Bike Sheds and the Saturday-morning show TX.

[10] He won a celebrity edition of the game show The Weakest Link, defeating Vanessa Feltz in the final round.

[21] In 2007 Slattery played Tom O'Driscoll in the feature film Lady Godiva: Back in the Saddle, and the Canon of Birkley in the Robin Hood episode "Show Me the Money".

along with David Walliams, Josie Lawrence, Clive Anderson, Humphrey Ker and Neil Mullarkey for the BBC Comic Relief show 24-Hour Panel People.

[29] Featuring his baritone voice, Slattery appeared on London's West End stages in the musicals Me and My Girl[30] and Radio Times,[5] as well as in the play Neville's Island at Nottingham Playhouse in 1994.

[32] In May 2006 he was a narrator in Richard O'Brien's Rocky Horror Tribute Show, at the Royal Court Theatre as part of the 50th anniversary celebrations.

[33][34] In 2017–2018 he was the eponymous star of Slattery Night Fever, an improvised comedy show on London's off-West End, directed by Lesley Ann Abiston.

[44][45] In 1996, Slattery's crisis culminated with a six-month period as a recluse, during which he did not answer his door or telephone, "or open bills, or wash...