Generally, the best thing to do is keep an eye on V/street and A/work for touring Thais. I don't know if Derby has any Thai massage parlours but I hadn't heard of any, and the days of Thai girls finding a patch and staying there seem to be gone - Anya in Birmingham being one of the few exceptions I can think of off the top of my head.
The touring girls seem to change over every Monday. The thread about weekly Chinese/Thai switch joints often brings things up to date but doesn't always include V/street links. You often find one or two extra on there who aren't on A/work, and occasionally the reverse is true. By Tuesday, most of the girls have updated their ads but I have seen one or two new ones appear on Wednesday.
