It's an anniversary celebration for a club I belong to.
He used to belong to the club, I bumped into him at the gym today, haven't seen him in years. We chatted for a pleasant 5 mins about the sport and went on our way.
Afterwards I thought oh, I could have invited him to the do, people would be pleased to see him, he might like to catch up.
As a non member, he'd have to come as my guest. I'm sure my train of thought has nothing to do with the fact that he's an attractive single man, similar age to me...