[b]#3579 found @ 16:25:00, cache 7 of 10 today.[/b]
I had worked through these puzzles over the course of several weeks with a view to finding them on a visit to St. Albans at the end of August, I managed to puzzle out six in the series myself and had help with the last two from Alistair and my Dad. In the end we didn't have time that trip, so we decided to have a look for them today on the way elsewhere.
I tried to solve this one myself by using an online tool, but it kept throwing up errors.
I knew my Dad used to teach Machine Code to students at Essex Uni in the lat 80's, so I enlisted his help. He plugged the programme into his still-working BBC Model B and before long, I got an email which began "The cache is at..." BINGO!
A quick find for Alistair & I today. He was rather taken by the EPROM we found in the cache.
Have a fave point for the brainpower required.