Fifteen minutes before I am due to leave for a night at Zeta, I am overcome by a wave of sartorial angst. It occurs to me that my standard-issue evening look (Earl jeans and Nikes) may not cut it. I dimly remember a friend having to spend an evening at the Hilton's Windows On The World bar (several floors above ground-level Zeta) flashing rather too much leg in a dress that was really only ever designed to be a top, having lent her boyfriend her trousers in the lobby, so that he could change out of his jeans. So I call and speak to a staff member, who says: 'No, there are no restrictions on denim and trainers as such. But do try and make an effort, eh?'