Hammonds and Rosenblatt Solicitors are defending the rival interests of advertising giant WPP and newspaper group Northern & Shell in multimillion-pound actions.
Northern & Shell filed a $5.5m (£3.2m) claim, accusing WPP of breach of contract, in the High Court on Friday 9 January, one day after WPP lodged claims in New York against the publisher over the non-payment of bills.
Ian Rosenblatt, name partner of Rosenblatts, is representing existing client Northern & Shell in the English litigation. He will instruct US lawyers on the company's behalf to defend the New York claims. He has instructed 4 Stone Buildings barrister Richard Hill as counsel for the High Court claim.
Hammonds is acting for key client WPP in the English litigation.
Northern & Shell, which produces newspapers such as the Daily Express, is alleging that WPP had agreed to provide 15 pages of advertisements for the US launch of gossip magazine OK! in return for an increase in advertising spend. However, Rosenblatt claimed that WPP had breached the contract by not finding the 15 pages.
In the US litigation, WPP is claiming that Northern & Shell failed to pay $10m (£5.8m) for advertising promoting the OK! launch. Marketing communications law firm Davis & Gilbert is representing WPP in New York.