I sat and chatted to Phill a few years ago, near Woodhenge where he was flint knapping. He made an axe and an arrow head while I was there. Apparently the way they tell the difference by sight is the older flint is darker in colour or so I was told by by a lady who was flint knapping in Plymouth Museum about four years ago. Also the older flints tools from the Mesolithic are a lot smaller.

Lubin