"Tesco – a massive supermarket chain in Britain at the time "
Yeah, they've only got 1 store left now, haven't they?!
On a more serious note, I remember the vouchers for schools scheme. But I don't think that's what killed Acorn off - not to that extent anyway. My school started to buy IBM PC hardware in the early-mid 1990's. They had a combination of Acorn machines and PC's. They even had 1 Mac but I don't recall which model. I liked the Acorn machines but remember that it was the application software on the PC's that simply blew them out of the water. I think as well (some) schools had a foresight to realise that as their students entered workplaces they'd be more likely to use IBM PC's and investing in anything further from Acorn would have been a bit of a backwards step. Essentially, it was good, but not for that long.