One of Paisner & Co's biggest clients, Great Universal Stores (GUS), has instructed Dibb Lupton Alsop to represent it in its battle against Knickerbox.
Paisner & Co has advised the Manchester-based company since 1932. A spokeswoman at Paisner & Co, who says that GUS is one of its main clients, says: "We do a lot of work for GUS including their litigation and intellectual property work."
A GUS spokeswoman says the company opted for Dibbs to represent it in the trade mark infringement case against Knickerbox because the firm is local.
Industry sources say Dibbs' Manchester office has recently been involved in other litigation work for GUS and claim the company has also started using the firm for work outside the region.
The GUS spokeswoman says: "The decision on external legal advice is not taken at board level but at a local level."
The dispute revolves around the use of the word "Kit", which GUS used to advertise a line of clothing.
However, Knickerbox has also begun using the name for one of its range, prompting GUS's lawsuit, which also demands any profits its rival has made from the underwear in question.
Nabarro Nathanson is acting for Knickerbox. Guy Heath, copyright and intellectual property partner at Nabarros, says: "We are vigorously defending the claim and counter claiming for revocation of their trade mark."
GUS also uses Linklaters for corporate finance work.
Dibbs intellectual property partner Graeme Orchison is undertaking the litigation.