A £450 million holiday scheme centred on a former theme park will be “one of the UK’s most successful tourism destinations” – if the Scottish Government says yes, it is claimed.

Paul Manning of Harcourt Developments made the claim just days before a Scottish Government inquiry into plans for Loudoun Castle estate is set to begin.

Spanning almost 580 acres, the site, near Galston in East Ayrshire, includes the ruins of the historic castle and was previously home to a leisure park named after the stately home. It closed in 2010, with many of its rides sold off and others left to rust.

Harcourt, the firm behind Belfast’s Titanic Quarter urban regeneration project, is now lined up to help turn it into a leading leisure and tourism site, turning the castle into a luxury hotel and creating 1000 energy- efficient homes as well as holiday lodges and a tropical water park.

The company has been brought in by the Loudoun Woods consortium, which had its bid for planning permission rejected by East Ayrshire Council last year.

Councillors refused the project on the grounds that insufficient evidence had been provided.

However, the matter was called in by ministers and the inquiry will begin in Kilmarnock on Monday.

East Ayrshire Council said it could not comment ahead of the panel.

However, David Mace, head of the Loudoun Woods consortium, said the blueprint will deliver “an all-weather, world-class holiday destination” that will attract travellers from outwith Scotland. No deal has yet been struck with Harcourt, but the group says it hopes to achieve this “very soon”.

On the significance of the deal, Mace said: “The fact that Harcourt is considering becoming part of the Loudoun Woods consortium and making a significant investment in Scotland speaks volumes for the quality and international scope of what we’re planning.”

The group aims to begin work next summer and says more than 1000 new jobs could be created.

Manning said: “We are engaged in very positive discussions and hope to be able to conclude an agreement to join the Loudoun Woods consortium.

“The site’s historic setting, great transport links and proximity to some of the world’s most famous golf courses, gives it massive potential to become one of the UK’s most successful tourism destinations.”

A-listed Loudoun Castle, which dates back to the 12th century, was once a 90-room mansion but suffered extensive fire damage in 1941.

Mace said: “Our vision is that Loudoun Woods becomes Scotland’s premier short-stay inclusive resort with the lodges and treehouses built sensitively amidst the forest landscape. It will be a traffic-free environment with cycle and walking paths linking the accommodation to the water park, hotel and other leisure amenities.

“The Loudoun Castle hotel will be the centrepiece of the development, allowing us to restore this historic castle to be enjoyed by future generations.”