After graduating, Mahoney worked with Colchester Rep and the Mercury Theatre before joining the
Royal Shakespeare Company in 1967 – he was one of the first black actors in the Company. He worked regularly on the stage throughout his career including shows at the
National Theatre,
Young Vic,
Royal Court,
Almeida and his final stage performances were in
Alan Bennett's
Allelujah! at the
Bridge Theatre in 2018. He helped found Performers Against Racism in the 1980s to campaign against
apartheid in South Africa and was Joint Vice President of Equity between 1994 and 1996. He was seen most frequently on
television in series such as:
Danger Man,
Dixon of Dock Green,
Z-Cars,
Special Branch,
The Troubleshooters,
Menace,
Doctor Who (in the stories
Frontier in Space,
Planet of Evil and
Blink),
Quiller,
Fawlty Towers (as Dr Finn in
The Germans, 1975),
The Professionals (as Dr Henry in the episode
"Klansmen", never transmitted on terrestrial TV in the UK, and in "Black Out", again as a doctor),
Miss Marple,
Yes, Prime Minister,
Bergerac,
The Bill,
Casualty,
Holby City and
Sea of Souls. His films included
The Plague of the Zombies (1966),
Omen III: The Final Conflict (1981),
Rise and Fall of Idi Amin (1981),
White Mischief (1987),
Cry Freedom (1987),
Shooting Fish (1997),
Wondrous Oblivion (2003) and
Shooting Dogs (2005). He featured in the
Channel 4 documentary
Random (2011), and in the
BBC Three drama
Being Human (2012) as
Leo, an aged and dying werewolf. Mahoney's last TV appearance was in the
Tracy Beaker CBBC spin-off,
The Dumping Ground, as Henry Lawrence, the grandfather of
Charlie Morris (
Emily Burnett). ==Campaign work==