Sir John Bourne, the head of the National Audit Office, said he wanted to access the accounts of the Duchy of Cornwall and the Duchy of Lancaster as MPs criticised officials over the Prince of Wales's income of nearly pounds 12m last year.
Managers of the Duchy of Cornwall - which provides Prince Charles with an income - were repeatedly challenged as they gave evidence to MPs for the first time in the estate's 700-year history alongside officials of the Duchy of Lancaster, which benefits the Queen.
Members of the Commons Public Accounts Committee likened the Prince's huge income to "winning the National Lottery every year" and accused the Duchy of "fiddling" by borrowing from its protected capital reserves.
Sir John called for public auditors to scrutinise Duchy accounts despite assurances that Treasury officials monitor all the estate's transactions.
He said: "I would like to have a look at the books ... the Treasury is part of executive government. I report to Parliament. If I looked at the books I would be able to report about the aspects that I think should be brought to attention."
But Bertie Ross, the secretary of the Duchy of Cornwall, rejected the demand. He said: "The Duchy of Cornwall income is private to the Prince of Wales. Any business or estate that's private should be able to choose its own audit."
Prince Charles and his sons receive no allowance from the Civil List, instead drawing an income from the Duchy of Cornwall. The Duchy is tax- exempt but the Prince pays income tax voluntarily. He spends pounds 5.9m on official and charitable work. Some pounds 4.4m goes on tax and on personal expenditure.
MPs criticised the scale of the Prince of Wales's income, which averages pounds 6m a year and has grown by 300 per cent over the past decade. Alan Williams, the Labour MP for Swansea, said the Prince's annual payments were the equivalent of 450 people on average earnings. He asked Mr Ross: "Don't you think pounds 11.9m is getting a bit excessive?"
But Mr Ross said: "It is for me to provide a proper income from well managed estates. For me to comment on the sums of money is not relevant on this occasion." He said the Prince funded his staff, official duties and charitable work through his Duchy income, praising him as "the biggest multi-purpose charitable institution in the country".
Mr Williams maintained his attack, branding the Prince's accommodation at Clarence House as "the best housing benefit scheme in the world".
Gerry Steinberg, the Labour MP for Durham, criticised officials for borrowing from their capital accounts. He said: "pounds 1.2m was borrowed from the capital ... It looks like you've been doing a bit of fiddling."
Mr Ross denied that the Duchy had broken rules designed to protect the estate's capital for future generations.
But Mr Steinberg said: "Both your organisations have no transparency at all. I could look at them and I could be looking at double Dutch."Reuse content