tudor with a chrome plated case?

[tudorguy]

hi all, hoping someone can help me out here.

got a 1950s tudor prince oysterdate with what appears to be a chrome plated brass case. would normally scream 'fake!' straight away, but the trouble is the back fits like a glove and says 20 microns plaque/laminate and it appears to be a good 50-60 years old judging by coloration and wear etc.

what could it be?

photos offer little help, but will post if you really want them.

case is definitely brass/copper material with a chrome plating.

thanks

Ben