Check behind those sofas! 100 days left until round £1 coins are no longer legal tender - and one in three still have some stashed around the house
Old round £1 coins no longer legal tender from 17 October
Royal Mint polls suggests one in three households have some laying around
Round £1 coins could become a future collectables
Millions of households have old-style £1 coins laying around the house, which will soon lose their legal tender status, according to the Royal Mint.
A poll by the Treasury-owned Mint suggests one in three have some stashed away in savings jars and piggy banks across the country – or roughly 9million households.
It comes as the billionth new 12-sided £1 coin passed through the Royal Mint's production line today, struck by Exchequer Secretary to the Treasury, Andrew Jones MP.
By mid-July there will be more new coins in circulation than old and people have already returned 800million of the old coins, more than half of the total circulation.
They entered circulation in 1983, replacing the £1 note.
The Minister is calling on the public to dig out these old coins before they lose their legal tender status on 15 October 2017.
Andrew Jones added: 'This coin is the most secure of its kind in the world and was brought in to clamp down on the multimillion-pound cost of counterfeits.
'In less than 100 days, the round pound will lose its legal status. So people need to spend, bank or donate them by 15 October.'
The Mint says that many of the round coins will be melted down to make the 12-sided ones.
Some have been collecting the round £1 coins before they disappear. Change Checker launched its '£1 coin race' in February which has proved popular, as people looked to get all 25 designs before the withdrawal date.
A spokesman at Change Checker said: 'As people add these coins to their collection and more are removed from circulation by the banks, they become significantly rarer.
'In change collecting the rarity of a coin has an impact on its value, some of the rarest £1 coins can sell for up to 35 times their face value on auction sites.
'It is hard to predict exactly now but a full collection of round £1 coins could potentially fetch you a pretty penny in years to come.
'If monetary value isn't your motivation, by collecting the round £1 coins, you will be owning a genuine piece of British history, something to be passed down the generations.'
The rarest of £1 coins has a circulation of under 1million - the 2011 coin featuring the Edinburgh coat of arms which had a mintage of 935,000.
Sold by themselves, they were selling for around £5 on online auction websites in December, which is far less than the Kew Gardens 50p – or any mentioned in our round-up of valuable coins that can turn up in your change.
However, as part of a full set and in pristine condition, it could be well worth hanging onto if you get one in your change.
Meanwhile, a builder who found an erroneous £1 with two dates printed on it has had the mistake confirmed by the Royal Mint, which could mean it would be sold for a tidy profit.