The director behind the National Theatre of Scotland's biggest hit, Black Watch, has announced that he is to leave the company.

John Tiffany, who was named best director at this year's Tony awards for his production of the musical Once, has stepped down as associate director for the National Theatre of Scotland, having held the role since 2005. His remit at the company was to develop new work.

Tiffany will continue working with the company next year, directing the touring production of Black Watch and an adaptation of John Ajvide Lindquist's novel Let the Right One In, which will premiere at the Dundee Rep. He has not ruled out returning as a guest director in the future under incoming artistic director Laurie Sansom.

His departure, which comes just after the end of Vicky Featherstone's tenure as artistic director, allows Tiffany to do more freelance work, capitalising on the success of Once, which arrives in the West End next March.

Prior to his appointment at the National Theatre of Scotland, Tiffany was an associate director at the new writing company Paines Plough and literary manager at the Traverse theatre in Edinburgh, for four years apiece.

In addition to Black Watch, which won four Olivier awards including best director in 2009 and has played to more than 200,000 people worldwide, Tiffany directed Peter Pan and The Bacchae starring Alan Cummings for the National Theatre of Scotland.

"Being associate director at the National Theatre of Scotland in its formative years has changed my life," said Tiffany. "From the first moments discussing possible ideas for our new programme, to Black Watch opening in South Korea, it has been a privilege and an honour to be part of the best theatre company in the world.

"This opportunity has taught me so much about theatre and I have grown as a person and as a director, learning from brilliant Scottish artists and audiences."