One of the largest shareholders in Merlin Entertainments, which operates major theme parks such as Alton Towers, Legoland and Madame Tussauds in the UK, has been told to seek buyers.

ValueAct Capital, based in the US, has advised Merlin chairman Sir John Sunderland to sound out private bidders. In reply, Merlin said that it regularly considers options "for driving shareholder value."

An open letter from ValueAct, with 9.3 per cent of the Merlin shares, said that the share price of the world’s second largest attractions company "did not reflect the underlying value of the company and may not in the foreseeable future.”

Merlin is worth £3.6bn, according to the latest stock market prices, but ValueAct said that this could be subject to a one-third premium. It had noted negative sentiment from the City that was helping to drive down the stock market valuation of the company.