Just done a bit of number crunching, and it you analyse the listings on AW and VS, there are only around 71 unique phone numbers being used by foreign girls in Lancs, with another 18 profiles with no numbers listed - at least half of which are abandoned accounts
Even then, you can probably reduce the phones by another 15-20 where girls are using multiple numbers. So you're looking at between 60-80 foreign working girls (including thais) in the county at most
That doesn't include girls who only work for parlours / agencies. If anyone can put a number on those, or ideas of how to find it, I'd be interested