Barry Lowenthal, former managing principal at HookMedia, joins the agency as media director, and Chris Tucker, formerly of Hachette Retail North America, joins as its chief financial officer.
Head of broadcast Mary Cheney, art directors Chris Brignola and Jason Stanfield, and copywriter Joe Stevens have also joined the agency, reporting to executive creative director Kevin McKeon.
Stevens and Stanfield join BBH from Black Rocket in San Francisco, and Brignola comes from Fallon in New York.
Hegarty, who had been dividing his time between New York and London, returns to London full time.
The New York agency has recently seen its billings climb to $140m (£99.4m) with new clients such as Ericsson and Noggin, the commercial-free, educational TV channel and online site from Nickelodeon and Sesame Street Workshop.
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