Insiders have told PRWeek that Collins, currently Google's director of comms and for UK and Ireland, will assume the role of European comms director.
It follows the news that the current postholder Rachel Whetstone is to become Google's VP of global communications and public affairs.
Whetstone, partner of Conservative strategy guru Steve Hilton, will be based at the company's Silicon Valley headquarters - initially on a fixed-term six-month posting.
She replaces Elliot Schrage who has joined Facebook in the same role.
Rumours of Whetstone's appointment circulated on US websites as early as May 9, and confirmation came last week.
Google had initially agreed that she would move to Silicon Valley permanently. But it appears concern over the implications for Cameron of losing his most senior aide led to a compromise.
Collins was unavailable for comment. See the magazine for further information.