The pound in your pocket may be worth less than you think

The number of fake pound coins in circulation may be twice Royal Mint estimates, says the BBC. Official figures suggest around 2.5% - or one in 40 - are copies, but coin testing companies say it is one in 20.

This would put the number of bogus coins in circulation at 73 million.

The Royal Mint is playing down the data, as it doesn't want to undermine public confidence in the coins. However, it has quietly redoubled its efforts to remove the fakes from circulation by testing more coins than ever before.

In the last quarter of 2008 the Mint removed 270,000 fake pound coins from circulation compared to 97,000 for the whole of the previous year.

The biggest problem, naturally, is in coin-operated machines. Possibly the best reason yet for a switch to contactless electronic payments.