He will take up the new role of head of digital services in January. Proximity London, which offers data consulting, direct marketing and interactive services, counts Shell, Wrigley's and Royal Mail among its clients.
Baker will look to raise awareness of Proximity London's digital work. Other areas covered by the agency include sales promotion and planning and buying.
Baker handed over the running of Agency.com's BT account to managing partner Andy Hobsbawn while he took a four-month break.
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