FD senior MD Andrew Dowler is set to decamp to rival City agency Finsbury, PRWeek can reveal.
Dowler is one of FD's longest serving members of its senior team, having joined the agency in 1993.
He will become a partner at Finsbury and a member of the board.
His start date at Finsbury is not yet known, as details of his departure are currently being ironed out. It is thought he is unlikely to take up his new post at Finsbury until the autumn.
It is understood FD communicated the move internally on Monday.
Dowler has specialised in M&A, restructuring projects and private equity deals, and has worked on high profile transactions such as Terra Firma's acquisitions of EMI and AWAS.
He also advised ABN AMRO on comms around the bank's bids from Barclays and Royal Bank of Scotland, and eventual sale to RBS.
Dowler also advised British Energy around its £5bn restructuring on all aspects of the company's communications, including relations with shareholders, bond-holders, analysts, the media and UK Government, and subsequently on the firm's £12.5bn sale to EDF.
He headed FD's British Energy account since the agency won it from Gavin Anderson (now Kreab Gavin Anderson) and Maitland in 2002.
Dowler also previously served as managing director of FD's consumer business and has worked with brands such as Scottish and Southern Energy, and National Express Group.
He is likely to be restricted in terms of the client relationships he will be able to take with him to Finsbury, but his new agency will expect his contacts in the corporate and banking sectors to generate new business.
Dowler is the second notable FD staffer to leave the financial comms business in recent months, following Giles Sanderson's decision to quit the agency earlier this year. The 15-year FD veteran joined management consulting venture, NewMarket Partners, in March.
FD still boasts 29 managing directors across its UK financial comms business and in February brought on board John Waples, the Sunday Times' business editor, at MD level.