A spokesman for Trinity Mirror confirmed that Brittin, who joined the company in 2004, left on Friday. It is understood that he will not be replaced.
Brittin's leaving will be seen as a blow to Trinity Mirror because he played a key role in the planning and execution of the publisher's marketing and advertising activity across the UK.
Google UK confirmed that Brittin started work at its London headquarters this week, where he will report to Dennis Woodside, managing director of Google's operations in the UK, Ireland and Benelux.
Brittin's new role will be UK-centric and he will work alongside the recently hired Ben Legg, head of sales operations for the UK and Ireland and Benelux, and Mark Howe, UK director of sales.
At Trinity Mirror, Brittin was made director of strategy in May 2006, prior to which he was commercial director of the regional division, where he worked on advertising, marketing, digital and business development in the regions.
Before starting a career in media, Brittin worked for seven years at management consultant McKinsey & Co examining the company's strategy and performance levels.
If you have an opinion on this or any other issue raised on Brand Republic, join the debate in the .