Sean O'Grady: Figures behind economic 'boom' do not add up?

There may not be much in it, but the royal wedding will probably have a negative net effect on the economy, and a small drag on its recovery next spring.

On a very conservative estimate (much more conservative than the CBI's £6bn) the cost in lost output of a bank holiday might be about £1bn. The UK generates about £4bn a day in output – less at a weekend and more on a weekday. For some – those toiling in hospitals, power stations and petrol stations, say – the bank holiday will be business as usual. But even if only one in four of us does nothing much on 29 April, then national output will be down by £1bn, perhaps more.

This will almost certainly exceed the extra £620m the event is expected to generate from tourism and extra sales of beer and tat – depending on how patriotic the British are in their buying decisions. Mugs made in China or Korea will deliver less of a boost to UK plc than those manufactured in the Potteries; downing German lager or French champagne will do little for brewers in Burton on Trent; and so on.

Some have pointed to the intangible, confidence-boosting effects of the happy day. Yet there is little evidence that comparable events, such as the 1981 royal wedding or the 1966 World Cup victory, had much impact. The 1981 wedding was accompanied by riots and looting, while the 1966 win was followed just over a year later by a 14 per cent devaluation of the pound.