Most of the manufacturers made something of the sort. Yours looks particularly good, as one would expect from Chatwood. I have seen them by Whitfield, which were just one of their fire resisting safes with 2 handles riveted in place. Milner made one with what was, effectively, the lock from a cash box holding the door. (I won't say "securing" the door). Yours is rather nice having that arm to hold the door in place.

There were some made for moving valuables around. There was an army surplus place near Doncaster a long time ago. They had any number of those. They were a plate safe design- i.e. no fire resisting lining and actually weren't half bad for the purpose. They had 2 fixing holes through the back- I suppose I should call it the base- anyway the surface opposite the door, so they could be anchored through the bed of a vehicle. I seem to remember those had a very hard undrillable plate over the lock.