This is a string vest, it is literally made of string. I believe these or a type like these were used by British troops in World War Two. I can find no markings nor a label. It's a small size chest fitting. The vest is 'knitted' loosely with fabric shoulder joins.

These were very common in the British military, I believe for a number of years. Don't think they're often marked, so it can be hard to pinpoint when they were made or who wore them. You've got a nice one!

Always worn against the skin, under a shirt. I've read different "reasons" for them -- some Army gents said it was "to keep your skin out of direct contact with your shirt" (making shirts last longer between washing/wearing out) and that it "provided air pockets" to keep you cool. In the RAF, I've read that it was used to give a few extra seconds before fire hit your skin, should your clothes start to burn.

I had not heard of the RAF use but it makes sense. I have seen a photograph of a Para (I think) chap wearing one over his shirt and under his smock; I wonder if it was used against the skin in hot weather to keep shirts dryer and ventilated and between layers in cold weather, to keep wet cotton away from the underlayers and trap warmth.  The one I have would be a tight fit to wear over a shirt so maybe the size varied. I still wear a string vest in winter, it's very affective.