The Cornwall Association of Local Historians said it was horrified that the head of the wizard Merlin has already been carved into a rock face at the medieval site

'This is a historical site for Cornwall and we urge EH to look elsewhere to hype the box office to increase revenues. Don't tamper with Cornish history,' the association said in a statement.

It has urged the organisation to reconsider its plans which include installing an imposing sculpture partly inspired by King Arthur and a compass installation reminiscent of the round table.

'We are appalled at what English Heritage is doing to Tintagel, one of Cornwall' s most historic sites.

As an organisation of over 200 local Cornish historians, we view with alarm the plans to turn Tintagel into a fairytale theme park,' the association told the Guardian.

Despite its long-association with King Arthur that English Heritage widely promotes, historians argue that there is no evidence to suggest he ever visited Tintagel.

The association told the Guardian that focusing on the 'mythical fantasies' that King Arthur was conceived at Tintagel guaranteed eclipsing the true history of the site.

It said: 'In fact, it should be the function of EH to help visitors learn the true history of this Cornish place, to begin to better understand what has gone on before and to preserve that heritage.

Historians argue that there is no evidence to suggest that King Arthur ever visited Tintagel