The first time I bought them in the UK it was by bank transfer, I don’t remember the site but apparently they held the coins in escrow and then when the bank payment was confirmed they release them to the buyer. They gave you a random code to enter as the payment reference, and said many many times not to put anything like “Bitcoin” in there. :) The release was pretty fast, so either the seller was really active or they used an API to monitor payments into the seller’s bank account.