Sky News has learnt that the investment arm of the Universities Superannuation Scheme (USS) could sign a ground rent agreement with Butlin's parent, Bourne Leisure Group, as soon as this week.

It will come as Bourne Leisure and its owner, the private equity giant Blackstone, continue to hold talks with at least one party about the sale of Butlin's operating assets.

Epiris and Bain Capital have been among the suitors to buy the holiday camps.

That deal has, however, begun to look less certain as auctions of businesses such as Parkdean Resorts and Boots have been abandoned amid growing turmoil in financing markets.

USS's ground rent deal with Butlin's is among the most prominent deals struck by the university lecturers' retirement scheme for years.

Established in 1974, USS has hundreds of thousands of members and billions of pounds of assets.

Among the private companies USS owns stakes in are Heathrow Airport and Thames Water.

Butlin's, which was established by its eponymous founder, Billy Butlin, in 1936, was put up for sale earlier this year with price expectations of about £600m.

Bourne Leisure, which also trades under the Haven and Warner Leisure Hotels brands, decided along with Blackstone to put Butlin's up for sale after concluding that it did not fit with the rest of the group.

Bourne Leisure also owns the Haven and Warner Hotels chains.

According to the brand's official history, Mr Butlin "felt sorry for families staying in drab guest-houses with nothing much to do" during a trip to Barry Island.

In its heyday, Butlin's operated from nine sites across the UK, entertaining one million holidaymakers each year with knobbly knees competitions and glamorous granny contests.

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The brand became such an entrenched part of Britain's popular consciousness that it provided the inspiration for Hi-de-Hi!, the long-running BBC sitcom.

Its fortunes waned with the explosive growth of opportunities for Britons to holiday abroad, but has enjoyed a resurgence as the pandemic has fuelled a boom in staycations.

Butlin's sites are at Skegness, Minehead in Somerset and Bognor Regis, the traditional seaside town close to the South Downs National Park.

USS and Blackstone declined to comment.