WW2 Survival Kit

I recently found an old metal box with a number of items and utilities in it in my attic recently. I was told be a relative it was my grandad's survival kit from World War 2. It has a metal drinker and a few other bits and pieces. It's fairly dirty and worn as well, but there's no serious damage done to it.

Does anybody know if this is worth anything? I've done a few searches but turned nothing up.

Thanks!