I once got a WG from GEA (blonde small one) for an outcall to mine, no extra charge, she did have a driver though who sat outside the entire time. I wasn't too far from the centre though.
On a previous occasion (a good few years ago) I stupidly booked into the etap then tried to make arrangements with a wg, think it was an agency, called up and they had issues that couldnt phone the hotel room (cheap and nasty, no phone), they said it would have been £250 (which was advertised for outcall, no idea who it was, I'm sure at those prices someone will know) but if I wanted to walk across the bridge for incall then it only be £150. Flat was in the new builds across squinty bridge with the restaurant on corner. Saved myself £100 going for the incall but had already paid £40 for the room . I know I know, stupid price I was paying for an outcall, think it may have been my first time and didnt know what to expect arriving at some random wg "house"