About 10 years ago I was walking along the Croisette at the Cannes Film Festival with actor Simon Pegg when I spotted a party taking place on the yacht of software billionaire Paul Allen. This was the Octopus, one of the world's largest gin palaces, and as the celebs and models thronged the deck it looked like so much fun that I suggested we try and crash it. "No way," said Simon. "What if I'm photographed being turned away? It would be really embarrassing."
Alas, Simon wasn't on hand to advise Paul McCartney on Wednesday when the ex-Beatle decided to try his luck at a Grammys after-party he hadn't been invited to. The result was humiliation on a global scale, as the world's press reported how he and his entourage were twice refused entry. "How VIP do we gotta get?" he quipped. "We need another hit."
Clearly, McCartney was hoping his fame would be sufficient to get him through the door, but when the bouncer failed to recognise him he had nothing else to fall back on.
As someone who perfected the art of gatecrashing in the 90s, I could have given him a few tips.
My greatest success was getting in to the Vanity Fair Oscar party in 1994, generally regarded as the Everest of professional party-crashing. I used the simple expedient of pretending to be another British journalist who happened to be on the guest list, and enjoyed a full 10 minutes of stargazing before he appeared at the entrance with his gold-embossed invitation. The only other person I know who managed this feat was a female reporter who turned up in 1996 with a pig on a lead. Claiming it was the pig from Babe, one of that year's Best Picture nominees, she sailed past the clipboard Nazis without a second glance.
I ended up working at Vanity Fair and moved to New York, where I developed a repertoire of techniques for gaining admittance to exclusive nightclubs. One tried-and-tested method was to bring along a female partner-in-crime and, as we approached the doorman, start screaming at each other, as if in the throes of a full-scale row. Natural human reluctance to get involved in a "domestic" meant the bouncer would wave us through.
Another effective technique is "slipstreaming", where you attach yourself to the tail end of a celebrity's entourage. This doesn't always work. I remember trying to sneak into a Halloween party during New York fashion week given by Kate Moss. I waited outside until Moss arrived, then fell into lockstep behind her seven hangers-on. Only then did I realise they were all dwarves. It was a fancy dress party and she'd come as Snow White.
There are some party crashers so gifted that such hurdles pose no problem. At the 2008 Sundance Film Festival, I joined forces with a Republican Party fundraiser. He was a good-looking gentleman from Georgia, and his method for persuading octogenarian widows to part with their life savings proved just as effective when it came to seducing bad-tempered bouncers. Bombarded by his honey-voiced compliments, they would melt before our eyes. Once he managed to talk us into a private dinner for Gwyneth Paltrow being hosted by Steven Spielberg - not possible for mortal man.
Once you get in, of course, it's always a terrible anticlimax, and not just because you don't know anyone. Robert Louis Stevenson's famous observation - "To travel hopefully is a better thing than to arrive" - goes double for party crashers. The thrill of bluffing your way past the gatekeepers always outstrips the pleasure of being at the party, however "exclusive" it is.
The writer Frank Conroy, describing his experience of making it into fashionable Manhattan nightspots, summed it up: "It was fun, of course, but it was a complete waste of time and energy. I wasn't at the centre of anything. There wasn't any centre."
This, ultimately, is why Paul McCartney's decision to try to crash the Grammys after-party is so mysterious. It was an event hosted by a 23-year-old rapper called Tyga whose only claim to fame is that he goes out with one of the stars of Keeping Up with the Kardashians. Why on earth did the 73-year-old co-composer of Sergeant Pepper want to go to his party?
You'd think he'd know better by now.