The family of Captain Sir Tom Moore has been ordered to demolish an unauthorised spa pool block at their home within three months.

Hannah Ingram-Moore and her husband, Colin, lost an appeal against an order to remove the Captain Tom Foundation Building in the grounds of the property in Marston Moretaine, Bedfordshire, following a hearing last month.

In her report, inspector Diane Fleming concluded that “the actual removal of the building should take no more than three months” after the appellants argued it would take a year to comply with the order.

The L-shaped building was given the green light, but after the couple applied for permission in 2021, the planning authority refused the subsequent retrospective application in 2022 for a larger C-shaped building containing a spa pool.

After Central Bedfordshire Council issued an enforcement notice in July requiring the demolition of the “unauthorised building”, the Planning Inspectorate has dismissed the family’s appeal.

In her written decision, the inspector said: “I accept that the appellant’s intentions are laudable; however, it has not been demonstrated in any detail how all of this would work in practice.

“In the absence of any substantiated information, I find the suggested public benefit would therefore not outweigh the great weight to be given to the harm to the heritage asset.”

During a hearing in October, chartered surveyor James Paynter, for the appellants, said the spa pool had “the opportunity to offer rehabilitation sessions for elderly people in the area”.

Ms Fleming’s written decision concluded the “scale and massing” of the building had resulted in harm to the grade II-listed Old Rectory – the family’s home.

The foundation is currently the subject of an investigation by the Charity Commission, amid concerns about its management and independence from Sir Tom’s family.

The charity watchdog opened a case into the foundation shortly after the 100-year-old died in 2021, and launched its inquiry in June last year.

Scott Stemp, representing Ms Ingram-Moore and her husband, said at the appeal hearing that the foundation “is to be closed down following an investigation by the Charity Commission”.

Sir Tom raised £38.9 million for the NHS, including Gift Aid, by walking 100 laps of his garden before his 100th birthday at the height of the first national Covid-19 lockdown in April 2020.

He was knighted by the late Queen during a unique open-air ceremony at Windsor Castle in the summer of that year.

He died in February 2021.