Great Britain Self-Adhesive Stamps

I have a fairly large bag of Great Britain stamps on paper. I would like to start soaking them for removal. However, I am aware that the recent GB self-adhesives are almost impossible to remove by simple water soaking. When were these non-soakable GB issues first released? I would like to do some pre-sorting to avoid unnecessary soaking of the self-adhesives.
Thanks.

Dbuss, I believe the first issuance of a self-adhesive commemorative series was the February 13, 2001 Cats and Dogs set.

There doesn't seem to be a firm rule regarding which commemorative stamps are self-adhesive and which ones have regular gum, but there are a few general guidelines. Most of the Christmas stamps seem to be self-adhesive, in long sets where there are multiple different face values, there is often one with the same design as the First Class stamp but with self-adhesive, which is in addition to the first class stamp with regular gum. The long sets where ALL the stamps are first class, they all seem to have regular gum Hope this helps a little

I had some luck with self-adhesives in very hot water with a drop of dish-washing soap.

Hi,
If I want to remove the self adhesive stamps from paper:

for US self adhesive stamps, I put enough alcohol based hand gel on the back of the paper to soak through the paper. Not a lot of gel, just enough to coat the back of the paper. After about 2 minutes, the stamp usually, but not always, peels off. The original glue is usually intact. The stamp is intact.
Hope this would work in British self adhesive stamps

Thanks for the advice. Examining the perforation tips helped a lot in sorting out likely problems. Nearly all of the commemoratives soaked off successfully. The Machins were mixed with the older ones coming off easily. Time to break out the Bestine.