Andrew Pharoah joins the chewing gum manufacturer as director of public affairs and comms EMEA and India - the top comms role in the region. He reports to Chicago-based Wrigley V-P of comms Susan Henderson.
H&K's European chief Andy Laurence said Pharoah's role would be assumed by colleagues until a replacement is found.
'Wrigley is an exciting company with clear ambitions for growth,' said Pharoah, who added that he would be joining the New York Stock Exchange-listed firm next month. 'I'm looking forward to starting an in-house role.'
Pharoah has headed H&K's corporate practice for eight years, taking over from Edward Bickham in 2000. Before that, Pharoah had been within H&K's public affairs unit since 1995. His early CV includes working for the British Road Federation as campaigns co-ordinator from 1992 until 1995, and for the Labour Party in opposition.
He has also worked on two general election campaigns at Labour Party headquarters in Millbank, serving as a national party official and being elected to Labour's student wing in the 1980s.
Pharoah said it was too early to say whether he would be conducting an agency review.
Since late 2005 the US company has been using Golin Harris for consumer work in the UK (PRWeek, 9 December 2005).
The Wrigley's brand, which has held 90 per cent of the UK chewing gum market, is increasingly under threat from rivals Cadbury and Hershey.
The Trident brand, which Cadbury acquired five years ago, has already taken an extra eight per cent of market share in the US under its new owners.
However, Wrigley claims it has blossomed in the UK since the smoking ban was implemented last July.
The company claims its UK sales have picked up since Trident was launched a year ago.
New pack formats, such as the 'bottle and envelope pack', delivered £30m in sales last year.