Not only does this strike me as entirely illegal, it's also pointless as this mind-numbing exchange indicates:

Mr Cotton says the staff refused to tell him how much he could have: "So I wrote out a few slips. I said, 'Can I have £5,000?' They said no. I said, 'Can I have £4,000?' They said no. And then I wrote one out for £3,000 and they said, 'OK, we'll give you that.' "

He asked if he could return later that day to withdraw another £3,000, but he was told he could not do the same thing twice in one day.

EDIT: not a day goes by in which we don't learn about another restriction of freedom in the UK, seems like.