Steffan trained at the Guildhall School of Music and Drama and is the Artistic Director of Invertigo Theatre Company and a Trustee of Arts Connection and National Theatre Wales. 

Previous work for Shakespeare’s Globe includes: Othello, The Winter’s Tale, Pericles, Romeo and Juliet, A Midsummer Night’s Dream and Titus Andronicus.

Other theatre includes: An Oak Tree / Derwen (Tim Crouch); My Body Welsh (Invertigo); Pilgrims (HighTide/The Yard/Theatr Clwyd); Y Tŵr/The Tower (Invertigo); A World Elsewhere (Theatre503); Journeying Boys (Barbican); Outside on the Street (Invertigo); and I Am Not Manuel (Teatre Lliure, Barcelona).

Film includes: Bohemian Rhapsody and Darkest Hour .

Television includes: The Innocents, Shakespeare Uncovered and London Spy.