
O'Riordan left the IPC published woman's title in December. In her new role she will advise clients on the best ways of reaching their audiences.
Before editing Marie Claire, O'Riordan was group publishing director of EMAP's youth division, overseeing titles including Bliss, J17 and Looks. She was also editor of Elle and more! magazines.
John Browns clients include BskyB, Orange, RBS Group, Virgin Group, Volkswagen and Waitrose