Prince William has been accused of making “empty promises” on royal reform by anti-monarchy campaigners, who claim the cost of the monarchy continues to rise despite fewer working royals.

The criticism came from Republic, which issued a strongly worded statement following the Prince of Wales’s recent interview for a programme with Canadian actor Eugene Levy.

The campaign group accused the heir to the throne of “shameless spin and dishonesty”, suggesting his remarks on change in the monarchy amounted to little more than public relations.

Graham Smith, chief executive of Republic, said: “The royals have been promising reform for decades. It’s all empty promises, an attempt to deflect from rising criticism and falling support.

Prince William accused of ‘empty promises’ on reform by anti-monarchy group

“The only thing William wants to slim down is his tax bill. The cost of the monarchy continues to rise, despite a fall in the number of front-line royals.”

Mr Smith claimed: “William and his family cost the country more than half a billion pounds a year. This is blatant abuse of public money and public office.

“He has refused to disclose his taxes, he demands greater secrecy under the guise of privacy, he continues to take a publicly funded personal income of more than £20m a year from the Duchy of Cornwall.

“William is not a man interested in reform, but in protecting his own privilege. His soft-soap media appearances need to be met with hard-nosed journalism and exposure.”

Graham Smith is very critical of the monarch

Republic’s claim that the monarchy costs more than half a billion pounds annually is based on its own analysis, which includes estimated security expenses not published in the Sovereign Grant.

The official annual report for 2023–24 put the cost of the monarchy through the Sovereign Grant at £86.3million, equivalent to £1.29 per person.

The report stated that income from the Crown Estate had delivered record profits to the Treasury, with the monarch receiving 25 per cent of those profits to fund official duties.

The Duchy of Cornwall, inherited by Prince William in 2022, provides him with an income that is used to cover both official and private expenses.

While campaigners argue this amounts to taxpayer support, the Duchy is legally defined as a private estate, though it is not subject to corporation tax. Prince William, like King Charles before him, has chosen not to publish his personal tax returns.

Polling suggests the monarchy retains majority support in the United Kingdom, though surveys have recorded lower levels of enthusiasm among younger generations.

A YouGov poll conducted in April 2024 found that 58 per cent of Britons believed the country should continue to have a monarchy, compared with 26 per cent who preferred an elected head of state.

Republic has said it will continue to campaign for the abolition of the monarchy and greater public scrutiny of royal finances.

Prince William is entitled to the Duchy of Cornwall’s annual profits | PA

Its comments follow Prince William’s appearance on The Reluctant Traveler, an Apple TV series hosted by Mr Levy.

During the programme, which was filmed at Windsor Castle, the 43-year-old Prince spoke about his hopes for the future, saying it was “safe to say change is on my agenda” when asked about the direction of his eventual reign.

The Prince also reflected on the impact of a difficult year in which both Princess Kate and King Charles were diagnosed with cancer, describing the past 12 months as “the worst year of my life”.

He spoke about family pressures, his children’s activities and his desire to bring “change for good” when he becomes King.