The agency, which comprises integrated agency Billington Cartmell, experiential agency Closer and creative agency Brave, has been fully acquired by Hutton Collins Partners, which already holds a minority stake in the business, for an undisclosed sum.
John Gellett has been appointed as the new chief executive of the group. He will be supported in his new role by Howell, a founder of Howell Henry Chaldecott Lury (HHCL) and former managing director of ITV.
Matthew Hooper, who founded Interfocus in 1989 and is currently a director of Afinium, is joining Billington Cartmell Group as non-executive director.
Gellett founded below the line agency ZGC in 1989 and sold it to Mosaic Group eight years later, becoming chief operating officer. He has also held managing director roles at The Communications Agency, Travel for Industry and Ovation London.
Billington Cartmell was founded 22 years ago and now employs 180 people, with clients including, GlaxoSmithKline, Unilever, Panasonic and Morrisons. Last year it generated over £16m in gross income.
Billington and Cartmell have no plans to return to the industry at present. They said in a joint statement: "We are very proud of what we have built: a truly market-leading integrated communications group with real core strengths in advertising, direct, digital, shopper and experiential marketing.
All of the management across the Billington Cartmell Group remains the same.
Howell said: "I have now seen the marcoms sector from the agency, client and media owner perspective and share Hutton Collins's conviction that there is an opportunity to build a new type of independent communications group based around the skills that Billington Cartmell has in abundance. That is why Matthew Hooper and I are delighted to be joining the Board to help John Gellett and the BC team achieve that goal."