Brydon, the agency's head of press and outdoor, steps up to the new role following the departure of MPG's head of broadcast, Jim McDonald, in December and the creation of teams who buy across media.
His new role will involve leading media trading across TV, press, outdoor, digital, radio and cinema. The agency is looking to appoint a head of press trading following Brydon's promotion.
Brydon joined MPG in 2007, having previously spent four years as the ad director of the Evening Standard. His 30 years in the media industry also includes stints at Abbott Mead Vickers, PHD and CIA.
Paul Frampton, the managing director of MPG Media Contacts, said: "Alan's breadth of experience across all media, together with his senior contacts across the industry, put him in the best position to oversee our trading operation."