His switch to the role of business development director comes one month after Masterfoods dumped Grey from its global roster, resulting in a £17.5 million drop in billings for Grey London.
Read takes over his new responsibilities from the agency's deputy chairman, Nicola Mendelsohn, who goes on maternity leave early next year. He will continue overseeing Grey London's Tourism Australia and Ben Sherman fashion accounts.
His brief will be to help the agency strike a better balance between its internationally aligned advertisers (including Procter & Gamble and GlaxoSmithKline) and local business, as well as winning more work from existing clients.
"Replacing the Mars business will be a high priority," Mendelsohn said.
"But we also have other gaps to fill, particularly in the retail and financial areas and in media."
Read said his new role was "about helping get momentum back again".