I like the locks found on old english briefcases. They are solid brass and most of them are able to be locked (assuming that the key did not get lost along the way). The option of locking it is not something I have ever used but maybe someone has a reason to lock his bag. Although I don't see a reason for this I do think that it would look funny if there were no keyhole. Much like a chest without nipples or a stomach without a belly button.
Unfortunately only one place sells a lock similar to the old design. The liston briefcase lock from www.abbeyengland.com. It comes in a round design and a "3-position" design.
