Necessity is the mother of reinvention. Cheers!

I was up in London the other day, for reasons which seemed good at the time, when who should I bump into but my old friend, Adrian Wardour-Street, the uncrowned king of PR. He was going down Lower Regent Street talking into a mobile phone and trying to drink from a bottle of Vittel at the same time, or, I should say, alternately.

(When I say he was talking, he was in fact uttering monosyllables. The same monosyllable. "Cheers". Over and over again. It must be the ultimate multi-tasking word in the English language.)

He rang off when he saw me, tried to take a long swig from his mobile phone, laughed when he saw his mistake and steered me into a nearby bar called: "Wasser Matter?", one of the new breed of trendy water bars which have sprung up all over London replacing all those trendy coffee bars.

He ordered a drink called an Incoming Tide for both of us (it's frothy water on the rocks, with a sprig of seaweed) and asked me how I was doing. This is unusual for Adrian. Being a big wheel in the world of PR, he is usually more interested in telling me who his latest client is. In fact, the first person he mentions in a conversation is usually the latest client addition.

"I'm fine," I said. "I spend my nights dreaming of funny jokes and my days trying to remember them. How about you?"

"Me?" he said. "I spend half my time trying to get clients on to chat shows, and the other half trying to keep them off."

"Why do you want to keep them off chat shows?"

"What? Oh, well, let's say for example that one of my clients was someone like Michael Barrymore. I'm not saying he is, but let's just say he was. Let's say he felt he was ready for a comeback. Let's say I didn't think he was ready. Let's say he was invited on to a chat show. Let's say that I really didn't want him to..."

His phone rang. He broke off and answered it. "Cheers", he said. Then he listened for five minutes. Then he said: "Cheers" again and rang off.

"Good news?" I said. "Bad news? Wrong number? Michael Barrymore telling you a funny story? Michael Barrymore telling you a not very funny story?"

"There are two diametrically opposed theories about showbiz," said Adrian, playing with his seaweed. "One is that you've got to do the same thing over and over again. The other is that you must always do something different. It's called reinventing yourself these days. I call it coming back as someone else. JK Rowling is an example of someone who does the same thing over and over again. If she suddenly came back as someone else and wrote a book about farms and ponies, or a book of poetry, the public would drop her stone dead."

"Right," I said. "I know what you mean. I once came across an adult novel by Richmal Crompton, who wrote all the William stories. The William stories are great. Her novels are deadly dull."

"On the other hand," said Adrian, "if people are getting tired of your act, or too many people are copying it, it makes sense to come back as someone else."

He fell silent. I sensed it had a connection with his last phone call.

"Who was that on the phone just now?" I said.

"Osama bin Laden is a funny bloke," he said, obliquely. "Give him a good idea, like turning his surplus al Qa'ida training camps into summer holiday units for the adventurous - Club bin Laden, I wanted to call it - and he turns up his nose. So then I suggest writing his memoirs, but he says he's got lots more to do yet. Then he says what he really wants to do is turn his video experience to good use and start a TV chat show. Who's going to dare to appear on the Osama bin Laden chat show? I ask you !"

"Well, anyone who is really longing for a comeback," I suggested. "Like - well, Michael Barrymore, for instance?"

Adrian stared at me.

"Do you know, I think you might be on to something," he said.

He dialled again.

"Cheers," he said into the phone. "Look, this is going to sound crazy, but I do think I might know of a TV chat show which might be right for you..."

I left him to it. I had suddenly remembered why I had come to London. To get the train back home again to sanity.