Andrew Lownie, who is writing a joint biography of the Duke and Sarah Ferguson, Duchess of York, raised the concerns as he reacted to news Andrew has found the funds needed to stay at Royal Lodge.

Prince Andrew was asked by King Charles to leave the Royal Lodge, but he is said to have found the funds he needs to show he can continue taking care of the property in Windsor

The King stopped paying for his brother's £3million-a-year security at the 30-room home last month, raising questions about whether Andrew would be able to remain living there.

Prince Andrew is said to have come up with the money to stay in his home after King Charles cut him off financially.

The Duke of York has previously spent millions on renovating the Windsor property, and will be required to pay more under the terms of the lease he signed in 2006