Does anybody remember some safes that were in almost every branch of Nat West? They were a steel plate safe which was mounted on a system of runners and were mounted under the counter of the chief cashier. They had a John Tann lever lock which had a press button locking system so that they could be locked without the key. The bolt of that lock was all that held them closed but behing the lock was a piece of steel strip which held back 2 auxilliary bolts to form an AED. If the lock was attacked the 2 round bolts would have held the door closed. I don't think they deadlocked out, but were mounted on springs.

What made me think of them was a picture of a safe on a current thread. Strange how memory works.