This is why female 'door supervisors' are a good idea. Paul's been threatened on a basic Alpha male level. He knows that intellectually he could possibly have these guys over the proverbial (unless one's a moonlighting professor of Higher Physics), but challenged and rejected on the grounds of inappropriate clothing, he has been reduced to a mere puppy, being given a lesson by one of the lesser males in the pack.
Young ladies thus employed would've said, "I know it's a jolly silly rule - and by the way, you look really cool in that Ben Sherman shirt and FCUK jeans - and personally, if it was up to me, I'd get rid of it, but I'm really, really sorry that I can't let you in tonight. But if you come back tomorrow, my love, in nice shiny loafers, there'll be no problem."
Then she'd brush an imaginary speck of lint off his shoulder (grooming the superior male) and give him a little peck on his cheek, signifying that his status was undented, she recognised her place in the pack as a naturally inferior one, happy only to serve him in his best interests, and that his full power as an Alpha would be restored as soon as he resumed social, rather than sports, footwear. Easy!