Thanks to a review posted by RandomGuy99 recently I now see that the girl who answered the door was actually Horny Thai MIMI:
External Link/Members Only This is definitely who I was offered and not Diana.
RandomGuy responded to a VS advert for Diana (here
External Link/Members Only) but was B&S with Mimi. He went ahead with the punt and gave Mimi a Positive review so maybe I was too hasty in walking away (but at the end of the day it was still a switch).
It looks a though these two girls are working together. If you book one it looks like you could be switched to the other.
Thanks to RandomGuy for sharing his review of Mimi - a good example of how posting reviews and intel benefits everyone.