I don't just think I can walk into a random bank and request a deposit to his bank account number and sort code either (doesn't he have to be a member of the same bank?)
Of course you can. This is the standard method, as some sellers don't trust online transfers and besides, your bank will probably charge you a fee for that. Also, you don't need an account at the same bank (or
any bank for that matter) to make a deposit to someone else's account. If the account is at the Bank of Foo, you can just walk into any branch of the Bank of Foo, fill out a deposit slip with his account details, hand the deposit slip and the cash to the teller, take your receipt and you're done. They won't even ask for your name. What's the problem?
The only real danger is if the seller just takes the money without giving you your bitcoins, though the same risk is present regardless of what method you use.
