Thank you. Nice to meet you all. Unfortunately, I don't have a camera, but you can see the stone from the link;
eBay - The UK's Online Marketplace
I don't think it's Charnley forest(although I can't guarantee it isn't), WOA, TOS, Arkansas or anything like this. I would guess it is Llyn idwal. Yellow lake stone is very different, also known as Llyn Melynllyn, two variations if I'm not wrong, one slate, and another one, with different composition. I can give you a review on the slate type if you would like to, in another thread.