Alexander Deane, who has also served as a former chief of staff to David Cameron, joins Bell Pottinger Public Affairs this week.
Big Brother Watch was set up by the founders of the TaxPayers' Alliance to fight intrusions into privacy and to 'help a future government roll back a decade of state interference in our lives'.
Under Deane's direction, Big Brother Watch produced researched reports on CCTV cameras, the DNA database, covert surveillance by councils and the use of data chips in dustbins.
Deane said: 'I'm moving to Bell Pottinger because I wanted to work with what I see as the top flight company in public affairs; I wanted to use my Conservative background to good effect in business; I am proud of what we've achieved at BBW and a voice for that approach to privacy and liberty can and should be heard in lobbying.'
Deane was Cameron's chief of staff during his time as shadow education secretary in 2005. He is also a World Universities Debating Champion.
In a separate move, BPPA is promoting Liberal Democrat consultant Stephen Lotinga to the position of a director.
The two new directors'
appointments come as Peter Bingle's agency looks to plug the gap created by the imminent departure of director Liam McCloy after seven years with the consultancy.
As reported last week, McCloy, a former aide to Jack Straw, is set to join Fleishman-Hillard as a director.