Sky News understands that ECI Partners is the frontrunner to buy TAG, which marked its 35th anniversary last year.

It was unclear on Wednesday whether ECI, which has owned companies such as Auction Technology Group, was formally in exclusive talks to buy TAG, but travel industry sources described it as the most likely buyer.

Among the other suitors earlier in the process were Livingbridge and Equistone, two other private equity firms.

Formerly known as The Appointment Group, TAG has become a favoured choice for celebrities making travel arrangements for themselves and their entourages.

The company was founded by John Gianquitto and Maurice Veronique in 1988, and now employs more than 300 people.

Three decades later, a majority stake in the company was sold to Apiary Capital, a private equity firm.

Its other publicly disclosed clients have included Depeche Mode, Foo Fighters and Jay-Z.

Travel industry insiders have said the company could now be valued at roughly £150m, although the level at which offers were being pitched was unclear.

ECI did not respond to several requests for comment on Wednesday.