Lawyers instructed by banking tycoon Sir Victor Blank have gone head-to-head with the Hampstead Garden Suburb Trust in a High Court battle over plans for an underground swimming pool.

Sir Victor’s lawyers attempted to persuade a judge at the Royal Courts of Justice on February 20 to pass an injunction preventing the trust from approving the scheme until further notice.

It follows plans submitted to the trust for a basement extension to a luxury six-bedroom mansion.

Sir Victor, 70, a former chairman of Lloyds Banking Group, has brought the legal action in light of objections from a group of about 12 residents, including top judge Lord Justice Leveson and TV presenter Richard Madeley, who live close to the proposed development.

The group fears that removing earth to dig the new basement could result in significant damage to neighbouring homes.

They are calling for the trust to explore the potential impact of the plans on underground water levels in the area and how this may affect houses near the luxury home.

During the High Court hearing, both the trust’s legal team and Sir Victor’s lawyers put forward their cases to the judge and now await his decision.

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”.

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.

The trust was unavailable for comment.