Been years since I stumbled upon a bird with a really tight one. Before I joined UKP. I normally go for size 4-8 girls who are/look 18-28 yrs. Unfortunately, size on the whole doesn't correspond with size of the hole. As a matter of fact the last one that really sticks in my mind belonged to a WG who was bigger than me lol ...and I'm no smurf.
EDIT: Doesn't necessarily have to be in London. I don't mind traveling a bit if it's worth it. Max 200/h