The firm wanted a fresh look at its comms approach following the appointments of Lyndsay Wright as William Hill's first head of investor relations six months ago, and Ralph Topping as chief executive last year.
Industry sources initially speculated that the firm may have wanted a new agency in light of the changing brief to help drive the company in a new direction.
Wright met with fifteen agencies before narrowing them down to a four-strong shortlist of Brunswick, College Hill, FD and Tulchan Communications. It is understood the pitch came down to a two-way shootout between College Hill and Brunswick.
Wright said: ‘We wanted a new set of eyes on what we are doing as a business and what we should be saying to the market. I am sure that the new team at Brunswick will bring that fresh perspective to us.'
Although staying within Brunswick, the account will be run by an entirely different team now led by partner Simon Sporborg.
The agency had worked with the world's largest bookmaker since its 2002 flotation.