Notes with low serial numbers in the first printing run have become prized collectors' items. (The first fiver – bearing the number AA01 000001 – was presented to the Queen.)

We will have to take a closer look at the serial number, as one of the first fivers to be minted with the serial number AA01 000017 just sold for over £4000 at a Birmingham Auction.

If you think that's a healthy profit, there is one on eBay with the serial number starting with AK47. It has had 107 bids and bidding is up at £80,100. Eighty thousand pounds. Let's just take a moment to absorb that (and run to check our fivers!)