In these times of austerity, a big public celebration like the Queen's Diamond Jubilee might be just the thing to cheer up the nation. But can we afford it?
The centrepiece of the jubilee is Sunday's river pageant - a flotilla of more than 1,000 ships and boats will sail in the Queen's honour from Hammersmith to the West India docks.
It will be a giant undertaking, but it won't cost the public a penny. All of the £10.5m budget has been raised from individual donations and corporate sponsorships, and a "substantial" surplus has been raised. It will be given to charity via the Queen Elizabeth Diamond Jubilee Trust.
Monday's Diamond Jubliee concert at Buckingham Palace will be another highlight of the weekend's celebrations. The artists are playing for free, and the costs of staging the production are being met by the BBC. However they have sold the event to over 140 countries - it would be surprising if the revenues from that do not also generate a surplus, which would be given to the Diamond Jubilee Trust.
Around the country, a number of street parties, lunches and other events will be funded by the participants. On Monday evening a network of 4,212 beacons will be lit around the country and the Commonwealth - all funded by local groups, such as Lions Clubs, parish councils and so on.
But the public purse is not entirely spared the cost of the event. The Greater London Authority has budgeted £2m for outside screens, road closures, signage and similar expenses. It will pick up £100,000 and pass the rest of the bill to the Department for Media, Culture and Sport. Some of the costs will be offset by revenues from commercial sponsorship.
The Royal Household has been given an extra £1m to cover the cost of administration and increased correspondence in the jubilee year. That comes from taxpayers via the Sovereign Grant - and it's more than double the contribution made for the Golden Jubilee in 2002 (£450,000).
On top of those costs, the Metropolitan police will put over 6,000 officers on duty on the busiest days. 21 police boats will patrol the river. All these costs will be met from the public purse.
Read more: Does the monarchy pay for itself?
Prolonging the recession
The Ministry of Defence is also making a big contribution. The type 45 destroyer HMS Diamond started the proceedings with a 21-gun salute at Portsmouth harbour on Friday - this will be followed by an RAF flypast, and 1,000 personnel from all three services will take part in the parades and fire salutes and a "feu de joie".
The MoD and Met police would not supply cost estimates for their participation, but it is likely to run to millions of pounds.
But the biggest cost of all will come from the time off that the public take to watch it all. The Bank of England warned that the impact of people not working on the bank holidays will knock 0.5 per cent off GDP for the second quarter of the year - wiping over £1bn off the national output and prolonging the country's double-dip recession. A lot of cheering up will be required.