The Duchy of Cornwall carried out a “major refurbishment” of a cottage for £340,000, its accounts revealed.

The Prince of Wales’s landed hereditary estate published its own financial report on Tuesday, which detailed the refurbishment of Myrtle Cottage on the Isles of Scilly.

Annual accounts for the Duchy were released on the same day as the Sovereign Grant figures, which showed the cost to the taxpayer of renovating the Duke and Duchess of Sussex’s Frogmore Cottage came to £2.4 million.

The Duke and Duchess of Sussex
The Duke and Duchess of Sussex have moved into Frogmore Cottage (Victoria Jones/PA)

Myrtle Cottage on St Agnes was underpinned, insulated, repointed, rewired, replumbed and dry-lined, had a new floor laid and was given a new kitchen, bathroom and Cornish Trevillet slate roof for £340,000.

Graham Smith, from Republic which campaigns for an elected head of state, said of the comparison of the two cottages: “I think it’s very telling that when it’s their own home, there’s no expense spared.

“They’re very shrewd when it comes to business, particularly the Duchy.

“This should be an investment which helps the local community on the Isles of Scilly which it certainly won’t because money keeps on going off the islands and never comes back.”

The Duchy report said: “During the year, a £340,000 major refurbishment was completed at Myrtle Cottage, St Agnes, Isles of Scilly.

“The building had previously been used as seasonal holiday accommodation, but after this comprehensive refurbishment it was able to be let to a local St Agnes family from this off-island community, where housing is much in demand.”

Janet Stewart, who now lives in the cottage, said in the report that she had waited 11 years for a family house to be available, and moved in last August.

The work was part of the Duchy’s commitment to add to the permanent housing stock on St Agnes.

“After living with my parents for all that time, it has been amazing to have so much more space,” Ms Stewart said.

“The children have a bedroom each, and we have been able to unpack belongings we haven’t seen in a decade.

“Being able to live at Myrtle Cottage has meant that we can continue living on the island for the long term.”

The Prince of Wales and Duchess of Cornwall on St Agnes
The Prince of Wales and Duchess of Cornwall on St Agnes (Ben Birchall/PA)

The cost of transforming Myrtle Cottage was met by the Duchy, rather than from public funds.

As heir to the throne, Charles is entitled to the surplus generated by the duchy’s vast portfolio of lands, buildings and financial investments – which includes the Oval cricket ground, 67,000 acres of Dartmoor and the Scilly Isles.

The Duchy’s total assets are more than £1 billion – coming to £1,099,748,000 in 2018/2019 – up £33 million from £1,066,505,000 the previous year.

Charles’s annual income from the duchy is £21.6 million.

Mr Smith added of the £33 million rise in total assets and Charles’s £21.6 million income: “It raises questions about the ownership of the Duchy.

“It’s the cash cow handed to Prince Charles by the state. There’s no reason he should be getting the proceeds.

“It’s a lot of money that should be invested back into local communities in Cornwall, Devon and elsewhere.”

The private landed estate was created in 1337 by Edward III to support his son and heir Prince Edward, known as the Black Prince, and all his subsequent heirs.

The exact details of the Myrtle and Frogmore Cottage renovations have not been revealed, nor the floor-area of the properties.

Frogmore Cottage has four bedrooms and a nursery, while Myrtle Cottage would appear to have at least three bedrooms. It is not known how many reception rooms the properties have.

Harry and Meghan’s official residence near Windsor Castle is a Grade II listed building.

Five small dormitory style units were converted back into a single home for the couple and their baby son Archie – with all fittings and fixtures privately paid for by the duke and duchess.

A royal source said the major work on Frogmore Cottage included replacing defective wooden ceiling beams and floor joists, updating outdated and inefficient heating systems, substantial new electrical rewiring, including its own electrical sub-station, and new gas and water mains.

Harry and Meghan paid for the fittings and furnishings privately.

The Duchy annual report also showed that discussions were held by its executive committee on “how best to deliver an increased programme of engagement for the Duke of Cambridge”.

The Duke of Cambridge
William will one day inherit the Duchy of Cornwall (Chris Jackson/PA)

William will inherit the Duchy of Cornwall eventually when his father becomes king.

Clarence House said that William was not stepping up his role with the Duchy.

The impact of Brexit was also highlighted, with the report saying it was the area that most concerned its agricultural tenants.

“Uncertainty resulting from the UK’s decision to leave the EU makes planning and investment decisions more complex, with future circumstances liable to change,” it said.

“In our recent survey, this was the area of most concern to agricultural tenants.”

It added: “Until clarity comes, it is hard to define a response or to understand the longer-term impact.”

Reflecting Charles’s interest in the environment and wildlife, the prince was instrumental in helping to set up a project in the Dartmoor area to help halt the decline in the curlew population.

He brought together interested parties in March 2018 at a local hotel which led to a five-year licence being granted allowing Duchy staff on Dartmoor to help by incubating the bird’s eggs, the report showed.

The Duchy has also been the subject of a BBC television documentary, following the day-to-day life of tenants and staff over the course of a year.

The two-part programme will be broadcast in the autumn.