Hartley's work includes designs for the National Theatre and Royal Shakespeare Company (London, Stratford and international), London West End theatres, Donmar Warehouse, Old Vic, Royal Court, Almeida, Hampstead, Lyric Hammersmith, Theatre Royal Stratford East, BAC, Bush, Bridewell, Coronet, Finborough, Gate, Kiln, King's Head, Menier Chocolate Factory and Southwark Playhouse. Other UK work includes Paines Plough, Theatre Royal Bath Productions, Sheffield Theatres, Bristol Old Vic, Birmingham Rep, Clwyd Theatre Cymru, Leeds Playhouse, Manchester Royal Exchange, Northcott Theatre Exeter, Wales Millennium Centre. Europe includes Ireland (Gate Theatre Dublin), Austria, Germany, Spain and Sweden. North America includes Broadway, Off-Broadway and regional. Australia includes Sydney Theatre Company, Melbourne Theatre Company, Bell Shakespeare, Belvoir, Griffin Theatre Company, Malthouse, Old Fitz, and independent companies including Little Dove Theatre Art, Siren Theatre Co, Red Stitch, Ride On Theatre. Opera includes Royal Opera House Linbury Studio, Opera Holland Park, Queen Elizabeth Hall, Castleward Opera Northern Ireland, Gothenburg Opera, Tiroler Landestheater Innsbruck, and Sydney Con. Worldwide design and touring includes South Africa, Hong Kong, Korea, Russia and Singapore.

C venues programmes and hosts over 200 productions and events at the Edinburgh Fringe each August at multiple venue locations in central Edinburgh. Buildings include original Fringe venues from the first days of the International Festival and Fringe, and some of the newest Fringe venues in the city. Alongside a broad theatre-based programme incorporating drama, new writing, physical theatre, musical theatre and children's theatre, C has developed a speciality programming immersive, interactive and site-specific theatre, and in hosting cabaret, circus theatre, performance art and cross-genre work. Established in 1992, C venues is a founder member of Edinburgh’s Associated Independent Venue Producers. C's productions have come from and toured around the world, and have won Fringe First, Total Theatre, Musical Theatre Matters and comedy awards.

C theatre is the in-house producing company at C venues and produces work at the Edinburgh Fringe and beyond. Pieces in our stable of regular work include Shakespeare for Breakfast, a new edition of which is created every year, and has performed at Edinburgh and overseas Festivals, and children’s and family theatre. C theatre has toured the UK and abroad as far as Poland, Singapore, Canada and the USA.