Heffernan was born in
Billericay,
Essex, England and worked as an usher at the National Theatre. He has appeared on screen in a number of roles, including Henry Lascelles in the
BBC adaptation of
Susanna Clarke's novel
Jonathan Strange & Mr Norrell,
Jaggers in
Dickensian and Steven Rose in the fourth series of
Luther. In 2017, he played
John Grigg, 2nd Baron Altrincham, in an episode of the
Netflix series
The Crown. He also played the Nine for Big Finish, in their
Doctor Who box sets
Doom Coalition and
Ravenous. He returned to the National Theatre in 2022 to play the co-lead opposite
Katherine Parkinson in a new production of
Much Ado About Nothing directed by
Simon Godwin. ==Filmography==