Elizabeth Hurley sometimes wears knickers, and Mariella Frostrup wears white cotton pyjamas. Sleep attire is a problem. I am still seeking The ultimate garment. I recently ditched two long white Laura Ashley numbers, which I decided were really not me - I had only ever worn them to tread the corridors of cold Scottish country houses, where you needed an A-Z to find the loo.

What I do have is a large collection of T-shirt, which, in the privacy of my own boudoir, are fine, but as soon as there is a risk that somebody else may see them, it all gets a bit embarrassing. There's the Wallace and Gromit one, the Gary Sobers one, the hideous Aruba one (which I bought for $5 during a bored hour in transit there), the Katharine Hamnett one (trendy, yes, but it says "Summer 1989") and, worst of all, a Saudi Arabian Airlines one, which says "1979" (I know, it's 18 years old, but I'm very attached to it).

Its not just me - everybody has these infernal T-shirts. If you stay the night with friends and have come unprepared, I guarantee that, along with a towel, you will be handed a greying, shapeless object which says "Australians do it upside down" or some other pithy one-liner. You then have to wear this, and realise that, like all your own T-shirts, which at the time of purchase were extra extra large, it too has now diminished, so that it sits about an inch above cheek level.

This is OK if you are male (in which case you probably wouldn't have been offered one in the first place), as it can be worn to the kitchen over your hopefully non-gaping boxer shorts, where you can happily chomp on some Cheerios before you go. But for us girls, it's not so simple. We have the option of trying to stretch said garment over our knickers (or worse still, G-string) and trying to slip into the kitchen and get our legs under the table before host and other, perhaps unknown, males spot our peeking cheeks. Or we can get into our party kit from the night before, which then necessitates the application of make-up and brushing of hair, or you feel like an old tart. Some friends recently had a house guest who descended to breakfast in teeny-tiny baby dolls, causing the husband to break out in a sweat and excuse himself, as he had only just got used to the Mothercare nighties of his heavily pregnant wife. It's a fine line.

If you are staying the night with someone in order to sleep with them, then it's a different matter. Nothing, or perhaps a pair of lacy little knickers that can come off in a trice, is all you need. If, however, you don't want to be so blatant about the purpose of your visit, you may want to employ the use of a call-his-bluff/red herring night garment. This must under no circumstances be the T-shirt. Men must avoid boxers with cartoons or love hearts, and silk ones are a definite no-no (obviously a gift from a tacky ex-girlfriend).

I have trawled the streets of London to find the classic, simple, sexy thing, so you need never worry again. Meanwhile, for me, it's Wallace and Gromit again tonight ...

Too sexy for my T-shirt

Pure and simple: short white strappy nightdress, pounds 18, La Senza, 162 Oxford Street, London WI

Impure and gorgeous: La Perla black lace and silk-chiffon nightdress, pounds 405, Selfridges, Oxford Street, London WI

Boy next door: "Authentic Underwear" boxer shorts in cool self colours, pounds 7, Marks & Spencer

Boy no more: button-fly boxer shorts, pounds 25, Emporio Armani, 112a New Bond Street, London WIA