Hartley is a lighting designer for theatre, dance, musicals, opera, circus and interdisciplinary projects, working internationally. He has lit for the National Theatre, RSC, Old Vic, Donmar, in the West End, for the Almeida, BAC, Bush, Coronet, Gate, Lyric Hammersmith, Kiln, Menier Chocolate Factory, Theatre503, Theatre Royal Stratford East, and at Birmingham Rep, Bristol Old Vic, Clwyd Theatre Cymru, Exeter Northcott, Leeds Playhouse, Manchester Royal Exchange, Sheffield Theatres, Wales Millennium Centre amongst others. Hartley has lit in the US on Broadway and regionally, and extensively in Australia and Europe, and his lighting has toured worldwide.
Recent work includes Land of our Fathers Theatre503, UK tour; Crave and 4.48 Pyschosis, Sheffield; The Ham Funeral Sydney; Misterman Sydney/Hobart/Edinburgh; Idiom circus-theatre, Berlin; Evangeline (movement), Canberra/Adelaide/Sydney; and The Wicker Husband (new musical), Watermill. Current projects include the new musical Indecent Exposure Southwark Playhouse.
Hartley is artistic director of C venues at the Edinburgh Fringe.