British sizes, and RAF jackets.

[Johnny L.A.]

I have a collection of flight jackets. I can't help it. Aviation is my favourite thing. One jacket I need for my collection is the RAF-issue Mk3.

Second topic first: Are these available for purchase, new? If so, where and how much?

First question second: Can somsone please explain sizing to me? I've heard that a size 4 is about a 44" chest, and a size 5 is like a 40" chest. The size of the jacket goes down as the size numbers go up? What's the inch size of s size 1? What's the highest size number, and what inch size is it?