Channel 4's Head of Scripted Comedy is to leave the broadcaster to form a new production company with Peep Show writers Sam Bain and Jesse Armstrong.

The writing duo (pictured, above) are best known for creating and writing cult-hit Channel 4 sitcom Peep Show, but their credits also include comedy dramas Fresh Meat, and Babylon, plus BBC comedies such as That Mitchell & Webb Look, Rev, The Old Guys and The Thick Of It. Their film career includes titles like Magicians and Four Lions.

The trio's new company does not yet have a name but is expected to begin producing programmes before the end of the year. Clarke will be replaced at Channel 4 by present Commissioning Editor for Comedy, Fiona McDermott.

Clarke will leave the broadcaster in April, but will also continue to work with Channel 4 as an Executive Producer on some forthcoming comedy commissions. Nerys Evans, currently Deputy Head of Comedy, is leaving the broadcaster after seven years to return to the production sector. Two new Commissioning Editors will be recruited.

Jay Hunt, Channel 4's Chief Creative Officer, says: "Phil not only has impeccable taste but is one of the nicest men in TV. Nerys is a fantastically creative commissioner and has been key to the department's success. We're lucky they've grown, in Fiona McDermott, a worthy successor who can build on the comedy department's fantastic track record. I'm looking forward to working with her."

Phil Clarke said: "After more than four years in the post, I can confirm that being Head of Comedy at Channel 4 really is one of the best jobs in television. It's been thrilling. I'm looking forward to returning to production, but consider myself lucky to have worked at the channel at such an exciting time."

Fiona McDermott says: "Phil's right, this is the best job in comedy and I couldn't be more thrilled and excited to be taking over the role, having worked together to shape some of our best loved and most successful shows. Here's to keeping C4 the most vital place in the country to develop and produce comedy."

Nerys Evans said today: "After seven brilliant years in commissioning I feel it's time to put my money where my mouth is and get back to programme making. It's been a genuine privilege to commission comedy for Channel 4, and in doing so support so many new writers and performers. I'm beyond proud to have had the opportunity to add to the amazing legacy of Channel 4 Comedy."

Jesse Armstrong's next project is Succession, a 10-part political drama for HBO in America in which Brian Cox plays Logan Roy, the tough, powerful, and aging patriarch of a family-controlled international media conglomerate.