As revealed in Campaign last week, Hainsworth has left the company after just one year in the post to pursue other interests (Campaign, 13 May).
Her two replacements will become the joint managing directors of the company, with Patten continuing in his role in charge of Media Audits' Dublin operation.
Patten and Brooke have been at Media Audits for three years, both having previously worked at media agencies. Patten formerly worked as a media director at PHD, while Brooke used to work at Initiative and COI Communications.
Julian Spooner, the chief executive of Media Audits, said: "We believe the best way to develop our business is to promote our internal talent."