By Rhiannon Mills, royal correspondent
The Duke and Duchess of Sussex's new family home has been renovated at a cost to the taxpayer of £2.4m.
The multi-million pound bill was revealed as part of the annual Royal accounts.
Frogmore Cottage, which was given to Harry and Meghan by the Queen, and is on the Windsor estate underwent six months of major building work before the couple could move in, ahead of the arrival of their baby son Archie.
The cottage had to be converted back into a single home after it had been turned into five separate properties used by royal household staff.
Sir Michael Stevens, Keeper of the Privy Purse, who is responsible for monarchy's accounts, said of Frogmore Cottage: "The property had not been the subject of work for some years and had already been earmarked for renovation in line with our responsibility to maintain the condition of the occupied royal palaces estate.
The Sovereign Grant covered the work undertaken to turn the building into the official residence and home of the Duke and Duchess of Sussex and their new family.
The building was returned to a single residence and outdated infrastructure was replaced to guarantee the long-term future of the property. Substantially all fixtures and fittings were paid for by Their Royal Highnesses."
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It comes after Kensington Palace had previously insisted that reports the renovation works would cost between £2m and £3m were too high, with the estimates closer to £1.5m.
A royal source said the major work included replacing defective wooden ceiling beams and floor joists, outdated and inefficient heating systems were updated, the home needed substantial new electrical rewiring, including its own electrical sub-station, and new gas and water mains were installed. Some work is still to be completed such as repainting the outside of the building.
Frogmore Cottage, which is owned by the Crown Estate, was a gift from Harry's grandmother. The royal source said: "The Queen has been informed of the progress of the project, throughout the project."
The palace said an allowance is provided for a new kitchen, bathroom and other features during renovations, up to a certain specification, but if a higher quality is wanted it is paid for privately.
Details have not been given about the fixtures, fittings and furnishings paid for by Harry and Meghan inside the early 19th-century building.
The details came out as the accounts for the Sovereign Grant, which funds the monarchy's official expenses were released. They show the monarchy cost the taxpayer £67m during 2018-19 – an increase of almost £20m on the previous financial year.