The figures, based on annual reports of Parliament's royal subsidies and Prince Charles's accounts, would seem to counter Clarence House's claim that the Duchess will not be a burden on the public purse.
The complicated and opaque financial arrangements have also led to calls for much greater public scrutiny over the Prince of Wales's private income.
Clues to the growing financial burden of supporting Camilla can be found in Prince Charles's own accounts. In 2003, before she was officially named as a part of Charles's entourage, the Prince's personal staff numbered just 17. This year's accounts reveal that the number of servants has leapt to 29.
Their salaries and the Duchess's own personal allowance are paid by Prince Charles out of the £13m partly taxed profits he made from his estates in the Duchy of Cornwall.
But it is the taxpayer who meets their travel and entertainment bills on royal tours. Public money also subsidises the "wear and tear" of the palaces that accommodate the offices of the Duchess and her staff.
The Clarence House press office, which is partly supported out of public funds, also fields a growing number of media inquiries concerning the Duchess. In the approach to Christmas the Duchess undertook a dozen or so official visits. But it is the massive costs of the couple's state-funded foreign tours that will provoke accusations of "mission creep".
The preliminary costs for the recent visit to the United States have astonished hardened royal watchers. The Foreign Secretary, Jack Straw, has told MPs that the estimated public cost will be £510,000, of which it is estimated that about £25,000 is additional costs incurred by the Duchess and her staff, who included a make-up artist, hairdresser and dresser.
The Foreign and Commonwealth Office says the breakdown of the costs means it will pick up the £180,000 bill for hotels, meals and entertainment for all staff. A further £330,000 of grant-in-aid was spent on the charter of the private jet to New York and associated travel costs.
The sheer scale is apparent when compared with visits Charles undertook in 2004 at the behest of the Foreign and Commonwealth Office. The total bill for all official visits subsidised by the FCO in 2004 came to just £86,000, while the total contribution from Parliament's grant-in-aid scheme was just over £1m. Charles made official visits to Australia, New Zealand, Fiji, Italy Jordan and Turkey.
Members of the Public Accounts Committee of the House of Commons have tried to tackle the "Camilla question". The MPs wanted to know the financial implications of Camilla taking up her official position as the first Duchess of Cornwall.
Ian Davidson MP, who sits on the committee, said: "Every man is entitled to have a wife but I would want to compare the costs of the Duchess of Cornwall with those of Princess Diana. If there was a considerable difference and this was being met out of public funds then I think we are entitled to know why."
The Public Accounts Committee has pressed Prince Charles to open his accounts to full public scrutiny. But Clarence House maintains that what the Prince of Wales does with his private wealth is his business. His advisers stress that he spends a large proportion of his Duchy profits on charitable causes.
THE BILL FOR A DUCHESS
* DUCHY OF CORNWALL COSTS
Personal allowance from Charles: £130,000 (a £10m trust fund will eventually provide her with an annual income of £400,000)
Two full-time secretaries: £100,000
Stabling of horses at Highgrove: £20,000
* Total: £350,000
* PUBLIC COSTS
Based on a 5 per cent proportion of Prince Charles's overall costs. The Duchess has the equivalent of five full-time staff, while Prince Charles has nearly 100.
Royal tours: £50,000 of total bill of £1m.
Parliament grant-in-aid for the maintenance of Clarence House: £62,000 taken from a total bill of £1.24m.
Financial support for Clarence House's media operation given by Department of Culture, Media and Sport: £4,000 from a total bill of £80,000.
Two police bodyguards, paid for by the Home Office: £100,000
* Total: £216,000
* Grand total: £566,000