A new £10 polymer note has been sold at auction, netting more than 700 times its face value.
At £7,200, the new note, featuring Jane Austen, raised more than double the auctioneer's estimate. It was, though, a rather special note, bearing the serial number AA01 000010 - the lowest number available to the public.
See also: New £10 notes worth as much as £900
When a new note is issued, the Bank of England always donates some of the lowest numbers, or those with a meaningful number, to some of the people and organisations that helped develop it.
Meanwhile, the first note of any new issue - AA01 000001 - is given to the Queen, with the next three going to Prince Philip, the prime minister and the chancellor of the exchequer.
Others, though, are auctioned off for charity - and for some reason, the new polymer £10 notes went for much more than was expected, selling for twice the price of the new £5 notes released recently.
Last year, the lowest-numbered polymer £5 note – AA01 000017 – sold for £4,150 in an auction that raised £200,000.
However, when it came to the new £10 notes, AA001 000011 sold for £5,200, while AA01 000014 went for £3,500. Further down the list of desirability, even AA01 000019 went for a still very respectable £1,800.
The cash goes to three charities: Candlelighters, Haven House Children's Hospice and Macmillan Cancer Support. Altogether, the 87 new £10 notes raised £263,200.
Collectors often queue at the Bank of England on the day a new note is released in order to snaffle one of the early serial numbers. On this occasion, though, they were disappointed to discover that they were given numbers beginning 'AH' instead - one reason, perhaps, for such high prices at auction.
Experts are warning, though, that these high prices mean that the notes are unlikely to keep their value over the long term. However, it's still pretty clear that any note beginning 'AA01' could be worth a lot more than its face value.
Before you spend any new £10 notes, then, it's worth giving them a quick once-over. While anything beginning 'AA' is most likely to be valuable, collectors are also interested in notes beginning with 'JA' - Jane Austen's initials.
Of these, the most likely to be worth something are naturally, JA01, along with JA75 - the year of Austen's birth.