Ian Millner, managing partner at Iris London, said: "We looked at the regional agency scene and found the category wasn't strong. We expect the agency to poach clients from London-based shops. Many northern retailers and brands would benefit from being serviced locally."
Humphris will be group account director and will join managing director Tim Gardner, former group marketing director of JD Sports owner the John Davis Group, who joined the agency at its summer launch.
Founding clients include Red Cinema, the rewards-based joint venture involving Manchester United and Village Cinemas International, and Ben Sherman clothing.
Humphris, currently on gardening leave, was unavailable for comment.
Colleagues at Blue Chip declined to comment because Humphris is seen to be joining a rival agency. But Blue Chip said it was on the hunt for someone to head the Kellogg's account following his departure.
Millner confirmed that Iris North is also looking for a senior creative and that an Iris office will launch in the US within three years. This year, the number of people employed by the agency has grown from 45 to 85.