nice post, maybe you'd should habe gone for digits first and then date, that way the conversation goes something like:
whats your number?
erm... I have a boyfriend
*big smile & joke* that wasn't the question, so what's your number?
oh its 07*****

Saying that though if you go in confident (like you did) I find if you keep the conversation sharp and quick it puts them on the back foot and they'll agree