Hi Bainbrig
Fair comment.
I didn't see the programme.
But, as you asked, how on earth can the machine count £20 notes and end up with an amount that is not divisible by 20.
It seems to me that the '999' display indicates that the machine is reporting an error
The only notes we have are in denominations od 5, 10, 20 and upwards, so the amount of cash in the pile of notes must have been divisible by 5. (Or were there some coins as well?)
Or maybe there were some counterfeit notes in there.
Or maybe there was, in fact, more than £1000.
I can't tell you. What I do know is that in the good old days (I left De La Rue in the 1980s), we would have to tell the operator there was an error.
We only had 7-segment LEDs in those days, so we'd tend to use the message 'Err', for system errors and '999' for 'too much cash' errors.
Interesting one....