Abbotts, who has a Liberal Democrat background, will become the fourth partner at the agency when he joins in September.
He left Lansons in March following the arrival of Andrew Silverman as director of public affairs. The time he has taken out is understood to be partly due to gardening leave.
Westbourne founder James Bethell said Abbotts would be the second Lib Dem at the agency, which employs five Labour-leaning staff, four Tories and ‘three or four don’t knows’.
Abbotts stood as a Lib Dem candidate in Sevenoaks in the 2005 general election and in Bromley in a 2007 by-election. He also worked in party headquarters in the 2010 general election and is a member of the Lib Dem communications advisory board chaired by Lib Dem peer and DLA Piper London managing director Lord Clement-Jones.
Bethell said: ‘Ben is one of those people who’s got a passion for comms, yet he was a Lib Dem candidate and is also commercially-minded.’
Abbotts’ agency career saw him join Lansons as head of public affairs in 2007 after three years at FD-LLM, which he had joined from The Communications Group.
Westbourne’s other partners are Bethell, Jennifer Powers and Paul Chapman. Bethell added that there was room for three or four more partners in the longer term.
The agency was founded in 2010 and handles public affairs clients including Siemens, Birmingham Airport and Shelter, as well as offering media relations services.