A former banking tycoon’s hard-fought battle to stop a basement swimming pool being built near his home is heading to the highest court in the country – even though the basement plans have never won approval.

Ham & High: Lord Justice Leveson. Picture: PA/Gareth FullerLord Justice Leveson. Picture: PA/Gareth Fuller (Image: PA Wire/Press Association Images)

Former Lloyds Banking Group boss Sir Victor Blank, 71, is bidding to take his legal fight against neighbour Scott Franklin’s proposed basement extension in Hampstead Garden Suburb to the ­Supreme Court.

His fight to obtain an injunction to stop Hampstead Garden Suburb Trust from making a decision on Mr Franklin’s plans was rejected at the Court of Appeal on Tuesday.

Sir Victor’s legal bills are ­believed to be spiralling into six figures, having already been forced to pay the trust’s £65,000 costs for the original High Court case.

He is one of a number of high-profile Suburb residents, including TV star Richard Madeley and judge Sir Brian Leveson, who are concerned that the proposed basement excavation – including an indoor swimming pool, a games room and wine cellar – could damage their nearby homes.

Sir Victor’s decision to try to take the case to the Supreme Court follows news that Mr Franklin’s basement plan was rejected by the Planning Inspectorate on March 11.

The inspector turned down the plans because the basement would damage one protected 80-year-old tree.

Lawyer Joanna Lampert, representing Sir Victor, said the Supreme Court bid was motivated by a “point of principle”.

She said: “It’s a long way ­removed from whether Mr Franklin should have his swimming pool or not. It’s a point of law.”

The trust has policies to protect the architectural standards of the Suburb and householders must obtain approval before making changes to the outside of their properties.

Last year, lawyers instructed by Sir Victor tried to obtain a High Court injunction to stop the trust from approving the basement plans.

It was argued that the trust would be in breach of its “covenant” with Sir Victor entitling him to “quiet enjoyment” of his home.

This claim was rejected by judge Mr Justice Henderson last April and the subsequent appeal was turned down by three judges at the Court of Appeal on Tuesday.

Trust manager Jane Blackburn said: “The Court of Appeal’s ­decision confirms the trust’s powers to preserve the character and amenity of the Suburb and is a welcome development.”

Sir Victor and Mr Franklin did not wish to comment.

The trust was set up in 1968 to preserve the character of Hampstead Garden Suburb, which was founded by Henrietta Barnett as a “model community for people of all classes living together in beautiful houses”.