Clifford Chance (CC) has clinched the key adviser role on the Royal Bank of Scotland's $7.3bn (£4.7bn) sale of its aircraft leasing business to Japanese banking giant Sumitomo Mitsui Banking Corporation

The deal, which has kept a large CC team busy for the last six months, is one of the biggest-ever corporate deals the firm has acted on for RBS.

CC is understood to have pitched against several magic circle rivals to win the work. Corporate partner David Pudge headed up the firm's team, which also included London corporate partners Joel Ziff and Simon Tinkler, the head of the firm's London corporate practice.

CC aircraft finance partner William Glaister, tax partner Jonathan Elman and antitrust partner Greg Olsen also also took roles alongside lawyers from CC's international offices in New York, Tokyo, Sydney and Shanghai.

Sumitomo's lead adviser is US firm Milbank Tweed Hadley & McCloy, which led the deal out of its New York office, with a team headed by Elliot Gewirtz, chair of the firm's global transportation finance department, alongside corporate partner Roland Hlawaty.

The sale is the largest-ever aircraft leasing company disposal, and the largest single disposal for RBS since being bailed out by the UK Government in 2008.

It follows a competitive auction process with three bidders, including China Development Bank and US bank Wells Fargo, with CC advising throughout. The sale is conditional on various antitrust and regulatory approvals but is expected to complete in the third quarter of 2012.

RBS Aviation Capital, which is based in Dublin, is the world's fourth largest commercial jet aircraft operating lease company with a fleet of over 200 aircraft. The deal also handed roles to two Dublin-based firms, with McCann FitzGerald assisting CC on Irish aspects of the deal, while A&L Goodbody took the same role for Milbank.

Commenting on the deal, Pudge said: "The most interesting and challenging part of the deal was managing the auction process against tight deadlines whilst maintaining the competitive tension given the current volatile markets."