It’s a dream home for just a tenner – but there could be a rather large catch.

A £6 million mansion on the North Norfolk coast being raffled off in a prize draw by Omaze – in a high-profile tie-in with the BBC’s Red Nose Day, backed by stars including Lenny Henry and Rylan Clark – is under investigation by council officials amid claims it breaches planning regulations.

North Norfolk District Council launched a probe after a member of public pointed out Larkfields, situated in the upmarket resort of Blakeney and designed in the style of the exclusive homes found in The Hamptons area of Long Island, appears to be larger than what was approved.

It means the winner – who will be revealed live on air during Red Nose Day next month – could find the substantial property caught up in a legal wrangle and possibly have to rebuild parts.

Omaze, which is billing the raffle as its ‘biggest ever Grand Prize Draw, insists it has done ‘due diligence’ and the mansion is legal – but has pledged that the raffle winner will not face additional costs if there are problems.

The whistleblower who tipped off the council, and doesn’t want to be identified, said: ‘It seems not to have been built to planning permission.’

Permission was granted for a previous property on the site to be demolished and a three-bedroom replacement built in 2020.

Further permission was granted the following year for the window sizes to be altered and a flat roof veranda to be extended.

But the eagle-eyed tipster claimed the 2020 floorplans differed from those publicised by Omaze, which purchased the property last July.

Areas that are being investigated include the east wing, described as a boot room, which appears much larger.

There are also outbuildings, a swimming pool and tennis court which are not mentioned in any planning applications.

If the grand home does breach planning permission, there is a chance it could avoid enforcement action because of the ‘four-year rule’, which allows retrospective planning permission if no objections have been raised during that period.

But NNDC’s planning portal shows the relevant certificate of lawfulness has not been granted.

Last year, the rules were changed to extend the minimum period for objections to ten years.

If Larkfields were not given retrospective planning permission for any reason, an appeal could be made to the Planning Inspectorate. But if that failed, the owner would probably be forced to demolish the illegal areas.

An Omaze spokesman said: ‘As with all its properties, Omaze and its team of expert professional advisers conducted a thorough due diligence exercise prior to purchase, to ensure that the property in Norfolk complies with all relevant planning and building regulations – as well as being of the highest design and build standards.

‘We are happy to confirm that the property passed all surveys and checks.

‘Omaze is looking forward to raising significant funds from this prize draw for its charity partner, Comic Relief.’

Omaze, which closes the raffle on Sunday, was founded in Los Angeles in 2012 but ceased to operate there in 2023 due to regulatory issues.

In the UK, it gives 17 per cent of sales to a charity partner with a guaranteed minimum of £1 million.

An NNDC spokeswoman told the BBC’s Local Democracy Reporting service that it was looking into the issue.

She said: ‘Officers will investigate matters raised to establish the facts.’