New York M&A powerhouse Wachtell Lipton Rosen & Katz is exploring the opportunity of launching its first international office in London.
Corporate partners Andrew Nussbaum and Stephen Cohen have been spending three or four days a week in the City since the end of August, analysing the benefits of a UK office.
It is thought Wachtell's motivation for the launch is a result of its close relationship with private equity house Apollo, which is also interested in acquiring Northern Rock.
An source close to the firm said: "There are partners who are stepping up their commitments to spending time in London. There's a core group of three to four partners visiting regularly. The big change is that the firm is going to London regularly. It used to be only when clients needed it."
Wachtell, an Apollo panel firm, recently advised the private equity house on its joint $15bn (£7.33bn) bid with Texas Pacific for US casino operator Harrah's Entertainment. The firm also scooped a role advising on Barclays' failed £45.5bn bid for Dutch bank ABN Amro.
The firm is said to be exploring the office launch primarily to serve a range of European clients.
The source said: "The firm has always focused on Europe, so really the increased visits do not change things. The point is to meet the needs of several clients, but Apollo is the biggest."
Despite Wachtell's increased presence in the capital, best friend Slaughter and May seems sanguine regarding a potential launch.
A Slaughters partner said: "We wouldn't bat an eyelid. Davis Polk & Wardwell has had an English office for some years now, but they don't practise English law.
"I'd say that Wachtell's world view has expanded rapidly in the past five years."
If the firm does launch an office in London it is thought it will not be offering UK law capabilities.
The source said: "Wachtell is not looking to hire lawyers whose job it is to do European work. The skillset covers very high-end US deals so people advising on those deals could be sent to Europe."