boojum
Ignoble Miscreant
I've decided I need something like this. I never got a Billingham, although they're very nice, but always used Domkes or similar which are still clearly camera bags that likely contain a nice camera. I'm not going out on a fashion runway, I'm going out to get photographs 😉
And you do not want to excite the interest of a would-be smash and grab thief. Army surplus stores or used shops like the Salvation Army or the like.