Thanks for the explanation. I know there are envelopes available for paying in money automatically, but I assumed they would need some kind of information filled in, ie how much cash was being paid in, and in what quantities.
I don't know if a voucher is safer in the post or not. It depends on whether someone searches the post for cash, and ignores gift cards, or if it's someone who just steals a quantity of post, and maybe just discards the gift card. In that case, although they wouldn't have stolen the value as such, they've still deprived the rightful recipient of it, and so wasted someone's money.
On the subject of transactions, I had a hassle trying to pay a utility bill today. There is only one bank where it is free to pay, and our local branch recently closed down, despite always being busy whenever I went in. I tried to pay the last bill at the branch in town, with a debit card, only to be told it was cheque only! Typically I didn't have my cheque book with me.
It can also be paid at the local Co-op, but several times when I've gone to pay there, the cashier informs me that they can't take it. I stood my ground this evening though, and politely told the (newish) cashier that I've paid it there several times in the past, so she said she'd try scanning the bar code and see what happened. Sure enough, it beeped to say it accepted it, and I duly paid!