He subsequently trained as an Assistant Director at Riverside Studios under David Gothard running a writer's group with Hanif Kureishi and directing new work by Stephen Lowe, Tunde Ikoli and Dario Fo, assisting on productions with Paines Plough, Foco Novo, the Royal National Theatre and the Theatre of Comedy Company.
He directed Berkoff's 'East' and the first stage production of Anthony Burgess' 'Clockwork Orange' at Edinburgh Festival, 'Requiem' with the dancer Gaby Agis at Leicester Haymarket, 'Milkwood Blues' with Allan Corduner at the Lyric Theatre, Hammersmith, Jean-Claude van Itallie's 'The Traveller' with David Threlfall at the Almeida Theatre and Heidi Thomas' 'Indigo' with Dougray Scott also at the Almeida.
[5] His extensive TV directing credits include Village by the Sea (from Anita Desai's novel in Sri Lanka), Case Histories, Silent Witness, Hotel Babylon, Strictly Confidential, Death in Paradise, New Tricks, Thieftakers, City Central, London's Burning, Waterloo Road, The Knock, True or False, Pie in the Sky, Sunburn, Out of the Blue, Staying Alive, Wokenwell, Merseybeat, The Bill, Holby City, Casualty, Eastenders, and the single drama Substance.
He directed the documentary Running the Bulls and six short films for C4, including These Colours Don't Run (with John Hannah), Fist of the Dragonfly (with Simon Russell Beale and Burt Kwouk), After the Party (with Jemma Redgrave and Morag Hood), Nightclub, The Return of Neville Dead, and The Loser (with Phil Daniels and Sean Bean).
In the United States, Boak has directed multiple episodes of Turn: Washington's Spies for the AMC Network, Rectify for the Sundance Channel, and Outsiders for WGN America.