Are you sure the 1st issue went as high as £5000?
The records I saw years ago never showed anything that high.
Only Crock £5k I know of is the red with clipped corners.
They may well have been using plaques from somewhere that had closed for the film shoot. 99% sure that was filmed in a studio set and not the actual casino.
Someone needs to rewatch the film and see if any more is revealed I guess.