Wanted: WWII movie with a broken record and pencil with a hidden paper inside

[galacticgirrrl]

WANTED: WWII MOVIE WITH A BROKEN RECORD AND PENCIL WITH A HIDDEN PAPER INSIDE

It is a b&w movie from the 40s-60s, probably British, from an outfit like Rank.

It has POW elements to it I think, Birdmen/Colditz type situation w/international POWs, higher type building rather than wood huts.

The one scene I vividly remember that is the key to locating it:

The prisoners smash a 78rpm on the table which is quite a shock and seems like a waste of limited resources of items you have in captivity until they pull out something hidden from under the record label (map? money? not sure now) Also from inside a pencil they pull some paper and unfurl it.

Thank you for any tips beyond John Mills or colour items.

gg