Martyn began his professional career in 1975 working backstage in various West End Theatres. His career progressed through Stage Management with The Nuffield Theatre Southampton and The Prospect Theatre Company, as a Production Carpenter for Kent Opera, a Production Electrician for The English Music Theatre, and as a Production Manager for The Tricycle Theatre, The National Theatre, Triumph Apollo Theatre Productions, and The English National Opera. He then Production Managed numerous West End and touring productions, including the original West End productions of Les Miserables in 1985 and The Phantom of the Opera in 1986. In 1988 he established his own Management Company, Martyn Hayes Associates, and amongst the productions the company worked on, he personally worked on The Phantom of the Opera in Canada, Japan, Austria, Germany, Sweden, and the USA, Song and Dance in Europe, Cats in Switzerland, Aspects of Love in London, and a private art exhibition in Poland designed by Franco Zeffirelli. Martyn was then appointed Head of International Theatre Production for The Really Useful Theatre Company in London, followed by positions as Manager of International Productions for Disney Theatricals in Los Angeles, International Associate Producer for Stage Holding in Amsterdam, and Managing Director of Stage Holding UK in London. In 2007 he joined Jacobsen Entertainment as Executive Producer and Director of Operations UK & Europe.