A new report out this week has estimated the total annual cost of the monarchy at £333.9m, eight times the official figure.

The report, Royal Expenses: Counting the Cost of the Monarchy, shows that each 'working royal' costs the taxpayer an average of £18.5m, making them the most expensive public officials in the country.

The report also challenges the claim that the monarchy brings in any revenue from tourism or the Crown Estate.

Campaign group Republic, which is publishing the report, has called for a radical overhaul of royal funding.

The report will be published on the morning of Tuesday June 23, ahead of the publication of the official royal accounts.

The report can be previewed at www.republic.org.uk/royalexpensesreport

Key findings

The estimated total annual cost of the monarchy is £334m, around a third of a billion pounds.

This means each ‘working royal’ costs the taxpayer around £18.5m a year on average.

The total annual cost of the monarchy is more than NHS England spent on the Cancer Drugs Fund last year.

For £334m the government could employ 15,000 new nurses14,000 new police officersor 15,000 new teachers.

Current funding arrangements are unsustainable and must be radically reformed

The report also shows that the monarchy is the most expensive institution of its kind in Europe. And with most funding going un-reported and the Sovereign Grant rising 29% in three years the whole system of royal finances needs a radical overhaul.

Graham Smith, Republic's CEO, has responded to the report:

"This is what happens when an institution is beyond proper scrutiny or accountability - public money is wasted and abused left, right and centre."

"How can the government continue to spend a third of a billion pounds on sustaining the monarchy when it is drastically cutting public spending?"

"With this kind of money we could be employing 15,000 new nurses or 14,000 new police officers. Instead we're flying royals around by helicopter and paying them multi-million pound incomes from the Duchies."

"This report represents a challenge to the government and the palace: come clean and spell out the full costs in detail and in full."

"This is also a challenge to the media, to scrutinise and report the cost of the monarchy more thoroughly."

"The palace's claim that they only cost each person 56p is just bad spin - would MPs get away with claiming their proposed pay rise will only cost us 7p per person?"

"Royal funding needs a radical overhaul - and this report sets out a simple reform charter that will stop the royals ripping off the taxpayer week in and week out."