As Scutty says it's only illegal for the punter if the girl is underage or trafficked, additionally the girls aren't doing anything illegal but the parlour and maid are when there is more than 1 girl working.
The reality is that authorities turn a blind eye to parlours who use legal girls; pay their taxes and aren't infested with drugs etc as it keeps girls off the streets and reduces kerb crawlers so out of sight of residents
I've seen signs at VIP indicating they have direct phone links / panic buttons to the police so basically operating with their knowledge.
Not been to VIP much over the last couple of years since Suzie stopped working there and nobody else really seems to take my interest but I have seen Lola (also at KSG Manchester) a few times and seem to keep returning to her.
As far as parlours go it's about as good as anywhere and i'd not visit any of the other ones in Preston as they seem to have a bad name