all good advice above......always be polite and friendly, but to-the-point and professional......don't be creepy......a very quick description of yourself might butter them up a bit.....ask them if they have questions or comments for you.......might want to hold off on the sexy preferences until the second communication just to be polite and discreet......don't associate any rate/money talk with sex, of course.......if all is a "go", be ready with a specific time and place early in the back-and-forth......
I'm sure you know all the above "rules" and followed them already!.......sorry it didn't work out with your London guy