Skadden Arps Slate Meagher & Flom and Simpson Thacher & Bartlett have won lead roles for Apax Partners as the buyout house closes in on a multibillion-pound deal that could become one of the largest European leveraged buyouts since the start of the credit crisis.

Apax is in exclusive talks to buy Denmark-based facilities giant ISS after putting in an $8.5bn (£5.5bn) bid for the company.