Reynolds Porter Chamberlain (RPC) has poached a tax litigation partner from its rival team at McGrigors.

Mark Whitehouse, formerly head of civil tax litigation at McGrigors, joins RPC as its first dedicated tax litigation partner during a period of flux for the tax litigation market, which boils down to a fierce rivalry between DLA Piper, Dorsey & Whitney, McGrigors and RPC.

In December 2005 a four-strong team from Dorsey led by barrister Simon Airey jumped ship for DLA Piper.

McGrigors has recently hired two barristers, including regulatory expert Jonathan Fisher QC, for its tax and regulatory team.

Whitehouse will work closely with RPC partner Fiona Walkinshaw, who has built up the firm’s tax offering since joining in 2003 from Andersen-tied Garretts.

However, Walkinshaw also handles commercial litigation work, meaning she has less time to devote to tax.

“Tax litigation is on the up at a time when commercial litigation is on the downturn,” Walkinshaw said.

Whitehouse arrives at RPC shortly after his senior assistant from McGrigors Guy Adams, with more hires on the way.

All four rival firms are involved in ongoing group litigation against HM Revenue & Customs, which involves hundreds of clients.

Walkinshaw alone is advising more than 60 clients in the Loss Relief Group Litigation.