Hannah Ingram-Moore and her husband Colin appealed to the national Planning Inspectorate against the demolition order by Central Bedfordshire Council.

Representatives for the family claimed at the appeal that the building "would enable Captain Tom's story to be enjoyed by the public" and could be used for coffee mornings and twice-weekly spa rehabilitation sessions for the elderly.

However, the inspector rejected the appeal, ruling that the size of the spa block was "at odds" with the couple's home - which is grade II listed.

The inspector also said that while the idea of opening up the building to the public was "laudable", she said there was no detailed evidence of how it would work in practice.

The family have been given three months to comply with the existing demolition order.

In August 2021, Ms Ingram-Moore and her husband were granted permission to build a Captain Tom Foundation Building on the grounds of their £1.2m home in Marston Moretaine, Bedfordshire.

The couple used the Captain Tom Foundation name on the first set of plans.

The organisation, which was founded in June 2020 in honour of Sir Tom - after he shot to fame by doing sponsored laps of his garden during the COVID pandemic - is currently being investigated by the Charity Commission.

The investigation is unrelated to the £38m Sir Tom raised for NHS charities with his own fundraising drive - for which he was knighted by the late Queen in July 2020.

The Second World War veteran died in January 2021, at the age of 100, after being treated for pneumonia for some time and then testing positive for coronavirus.

Plans for the site said it would be used partly "in connection with The Captain Tom Foundation and its charitable objectives".

However, the foundation's name was not used on the subsequent retrospective application for a larger building containing a spa pool, which was refused by the planning authority in November last year. At the time, the block was partially built.

Read more:
Why is there an inquiry into Captain Tom Foundation?
NHS charity distances itself from foundation

Planning bosses at Central Bedfordshire Council said an enforcement notice requiring the demolition of the "now-unauthorised building" was issued in March this year.

In documents appealing against the notice, the family said the building was "no more overbearing" than a previously approved planning application and the "heights are the same".

It also said the building was set at the back of the site, meaning it was not an issue for public view.

However, the Planning Inspectorate, to whom Ms Ingram-Moore appealed against the demolition notice, ruled that the "form of the new building is disproportionately broad and is at odds with the pleasingly domestic scale" of the main house.

"I find the erection of the new building erodes the positive contribution that the setting, provided by the extensive grounds, makes to the [main property]," inspector Diane Fleming found.

However, she found that the building had not caused "unacceptable harm" to the wider neighbourhood, as it was largely out of view from the property's grounds.

Ms Fleming also addressed a suggestion, put forward on behalf of the family at the appeal, that the new building would enable "Captain Tom's story to be enjoyed by the public" and be "supported by the appellant's personal charity work".

This included the suggestion of opening up the spa pool for rehabilitation sessions for elderly people in the area once or twice a week.

The inspector said in her ruling: "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."