I think I will take my money one hour earlier.

Where's everyone keeping their money after they've taken it out?

What will it achieve

If the banks DO crash and burn, then lots of innocent people who didn't get their money out in time might suffer. Most likely the vulnerable and less astute people, whilst the rich people with accountants in their pocket will be on the ball more and avoid the bankruptcy.

Completley pointless and destructive to the working class workers

if everyone else is doing it, i suppose i'd better do it too! however as the previous user said, the fatcats who own the banks won't suffer, all their money is secure (on offshore accounts in Monaco), in fact they'd probably receive extra compensation from their tory government cronies for loss of fortune. Interesting idea though!

In theory, what would happen (if anything) if EVERYONE in the UK burnt a £10 note?

Take my advice, get a sharpie, go outside, write 'revolution 20.11.2011, repeat step 1, ????, PROFIT'