This is significantly higher than the Sovereign Grant, which funds the Royal Family’s official duties and is set for a significant increase of over 53% to £132 million next year, up from £86m.

This rise is attributed to substantial profits from the Crown Estate, which were reported earlier this year.

Republic is calling on the government to slash the royal budget before making any cuts to welfare or the NHS.

The huge bill for the royals includes lost income from the Duchies of Lancaster and Cornwall, as well as an estimated £150m security bill, costs to struggling local councils and lost revenue from state buildings used exclusively by the royals.

The new report claims to provide “irrefutable evidence” that the two Duchies are state property, not private estates.

Speaking for Republic, CEO Graham Smith said: “This new report shows unequivocal proof that the Duchies are state property, not private estates. That means we effectively pay William a personal income of £23m a year.

“Republic is demanding the royal budget be slashed to below £10m, that only Charles receive any public funding, that he is given a salary pegged to that of the prime minister and that MPs hold a inquiry into this appalling waste of money.”