He has probably a near persian ancestry. MAY be british ancestry, but persian is more probable. Persian of old type perhaps?
What Im wondering on, he seems to have the beginning of the renown tabby M on his forehead. May he have a weak reddish masque on his face, reddish backside on the ears, and tail? blue eyes? IF so, he is a point and thus, may even be a decently purebred himalayan persian. (creme lynx point)
himalayan persians tends to not be as flatfaced as the other modern persians.
Of course, without solid proofs, he must be counted as a domestic medium hair - possibly long hair.
Aha, I see you are from Thailand. It makes it much more probable he is some sort of old type persian. Few breeders of modern flatface persians around there, I imagine.