Freshfields Bruckhaus Deringer has landed the headline role on the initial public offering (IPO) of over-50s holiday company and insurer Saga.

The float – the largest on the London Stock Exchange since the Royal Mail's IPO in October 2013 – seeks to raise £550m from a 25% share sale, which Saga said would reduce the company's net debt to £700m.

Saga is wholly owned by Acromas, the holding company backed by private equity investors Charterhouse, CVC and Permira, all of which work with Freshfields' corporate team.

Freshfields corporate partner Chris Mort is leading a team advising Saga on the listing.

The lawyer has previously led on the IPOs of more than 20 FTSE companies, including BSkyB, Debenhams, William Hill and Halfords, and acted for CVC on its acquisition of Formula One in 2006.

One of Freshfields' most high-profile partners, Mort was executive chairman of Newcastle United between 2007 and 2008, after advising owner Mike Ashley on his takeover of the club.

The Saga deal is also a coup for Freshfields over magic circle rival Clifford Chance (CC), which advised Permira and CVC on the £6.15bn merger between the AA and Saga at the height of the buyout boom in 2007.

For that deal, CC fielded a team led by James Baird, who has since retired, and Kem Ihenacho, who is departing the magic circle firm for Latham & Watkins.

Last July, a Freshfields team led by structured finance partner Marcus MacKenzie advised a consortium of banks on the £3bn refinancing of the AA, which allowed the client to partially pay for the debt it took on when it merged with Saga.