Replacement glass for Longines Conquest

[Hard-Drive]

I've got a vintage Conquest, Munich 1972 edition, and I think that the glass has at some point been replaced with plastic. Just does not feel cold enough for glass if that makes sense!

Where would the best place be to get it changed, and any idea of cost, or even if it's available/viable for the watch?

[Hard-Drive]

Oh what a muppet. Happened to be in Brum today killing some time before a meeting so I popped into Watches of Switzerland. Who politely informed me that a Longines Conquest of that vintage does indeed have a plexiglass face, not glass!

D'oh!

Happy though!