Iwas looking hard at a photograph of Kate Moss the other day. She was pictured in a feature about a house she had rented. The owner complained that the place had been turned into a pigsty. There were pictures to prove it. He was wrong. The place didn't look like a pigsty. It looked more like a war zone. But I wasn't so interested in the havoc wreaked during the Moss tenure. I was interested in Kate Moss's face. I was trying hard, yet again, to memorise it.

Am I the only one? I can never recognise Kate Moss. Not only am I not sure what she does, I cannot recognise her when she is doing it. I have been told often enough that she is one of the most famous people in the world, so naturally I expect her to be recognisable. Yet faced with a photograph of her, I say to myself in genuine puzzlement, "Who is this woman and what is she doing in my newspaper?"

What makes Kate Moss difficult to memorise is that she does not seem to have any memorable features. It is not as if she is stunningly beautiful, or so I deduce from her photos. She is, in fact, disarmingly average-looking. A lot of models have super cheekbones and look impossibly beautiful, like a cross between American squaws and thoroughbred racehorses, so that you don't know whether to fall passionately in love with them or offer them a sugar lump. But Kate Moss is different. I could never fall in love with her or share my sugar lumps with her. Apart from everything else, I know I would never recognise her when I next met her, which might bring any budding friendship to a quick halt.

I am not saying there is anything wrong with being ordinary looking. Some of the greatest beauties have been very ordinary looking. The other day I wandered into the National Portrait Gallery to look at Cecil Beaton's snaps of the famous, and found myself looking at Señor Mario Testino's more modern snaps of the famous. Two of them were of a gawky, heavy-boned, rather plain woman, who turned out to be Princess Diana. It had never occurred to me that Princess Diana was a plain Jane, but if the camera does not lie, she was. I would never have recognised her if I passed her in the street. Come to think of it, I never did.

I know it is not Kate Moss's fault, because I have had this trouble for a long time. Not being able to recognise certain famous people. It all started with Julie Christie. When I was young and newly married, I used to see this picture of a fabulous, flawless blonde in the papers, and I would say: "Whoever this woman is, she can be in my paper any time she likes!" and my first wife would say, "It's Julie Christie". "Julie Christie, eh?" I'd say, and I would carefully memorise her features. But it was no good. The next time I saw a lovely blonde in the paper, I wouldn't know who it was, and it was always Julie Christie, and it was always my wife who had to identify her, which diminished the fun a bit. It got to the point that whenever I saw a strange blonde in the paper, I would say, "Ah – Julie Christie!" Then my wife would say: "No – that one's Monica Vitti."

One day my then wife, who worked in museums, said she was bringing home an archaeologist friend called Rosemary for tea, together with her daughter, and I said, Fine, I'd be there. And Rosemary turned out to be one of those enchanting petite older women who I found irresistible even when young, and her daughter was a handsome tall person, and we all got on very well, and when they had gone, my wife said to me: "Well – what did you make of Julie Christie?"

My head swam. My jaw dropped. The rest of my body also swam and dropped. I suddenly realised that I had been chatting politely to Julie Christie, Rosemary's daughter, in my own home and hadn't recognised her yet again! I had failed the ultimate test.

There is no moral to this tale, really. Except that next time Kate Moss wants to rent a house in the country, I am about the only person in Britain who wouldn't recognise her and would unsuspectingly let her have the keys. It's just as well that I haven't got a house to let.