Ashurst Morris Crisp has raked in fees estimated by rivals to be worth between £2m-£3m advising the Stationery Office Group on its complex four-way demerger.
Private equity partners Charlie Geffen and Bruce Hanton were among 30 lawyers acting for the group, advising on the split of a varied selection of businesses, including its security printing division, which produces UK passports, and its publishing business, which produces 88 million pages of parliamentary documents each year.
The other two businesses were an office supplies division and a document management operation.
The elaborate deal involved a Section 425 scheme of arrangement and a Section 110 reconstruction.
Ashursts also advised on new debt financing arrangements for the new companies.
The deal followed the company's decision, taken at the end of last year, not to float. The company, which was privatised in 1996, chose to demerge because of fears that a flotation would have undervalued it as a conglomerate.
Following the demerger, most of the businesses are expected either to merge with other businesses or be targets for takeover.
Geffen said: "It is unusual for a private equity-backed company to go through a demerger as complex as this."