He had been working at the agency on a project basis for the past year on accounts including FullTilt Poker, Tate & Lyle and The Prince's Trust, and led the launch of Best Buy Mobile in the US. The CHI executive creative director, Ewan Paterson, said: "There is no better writer in the industry. Nigel will be a huge assett to the agency."
The move sees Roberts split from his partner, Paul Belford. The pair were the former Ogilvy & Mather and Abbott Mead Vickers BBDO joint creative directors.
Roberts began his career as a copywriter at Saatchi & Saatchi, before stints at DMB&B, Leagas Delaney and TBWA Simons Palmer.