I HAVE been told, by a drunk admittedly, that you can tell the personality of an individual by the colour of his underpants. Well, I don't know if there is any truth in this or not, but after a week or so at high altitude one's perception of colour can be impaired. It's amazing how welcome items of equipment are when they're donated - usually for promotion. That's what brought underwear to mind - the donation of paper underwear on a major expedition. It may seem a good idea in theory, but one must be aware of Greek gifts and all that. Perhaps they would stand the strain if you sat on a computer stool all day or have more hotpant appeal if they were manufactured from page three of a tabloid newspaper, but they're not for scaling mountains !

I recall an expeditionary wag writing on a packet of green paper boxer shorts: ''Please use discarded items of paper underwear in loo of toilet paper.''

Long Johns have a classical if not mystical ambience - the ''in'' gear of the 49'ers. New worlds were won in such apparel, peaks scaled and tundra crossed (For warmer climes Empire building shorts were then the order of the day).

Alas, though Long Johns enjoy a resurrection with the impetus of modern skiing and the frigidity of towbars queues, global warming may yet see them back in the bottom drawer.

I can understand the urge to collect autographs, after all it's on the cards that in due course they'll be sellable items, but not used Long Johns! It's common practice, after an expedition, to donate discarded items of ''polite'' clothing and gear to those master traders, the Sherpas, but not with used underwear! I once discreetly wrapped my close companion of three month standing, shroud - like round a rock and dropped it into the bowels of the glaciers digestive system, a deep crevasse, I assumed that they would be ground to the consistency of the aforementioned paper ''mache'' underpants in a matter of weeks. In this instance it was not to be, as I discovered when I got back home. A pal told me he had spoken to a trekker who had bought my name tagged Long Johns from a Sherpa at Namche Bazaar! It's always puzzled me how they were retrieved.

Don Whillans, when he was on the International Everest Expedition, was disconcerted to find a dead Sherpa in the small melt stream on the Khumbu Glacier, which was the Base Camp water supply. It's not just in the colder regions of earth that Long Johns come into their own with their go-faster rear bomb flap; an essential extra for sub zero squats. The whole business of going to the ''gentlemen's room'' at altitude or in Arctic regions requires premeditated planning. Fortunately, calls of nature are not so frequent at altitude as liquid input is much reduced. All water, unless you get melt water during the day, is painstakingly manufactured over an oxygen starved stove from snow and ice. What surplus liquid you have during the night is usually disposed of in your pee bottle which must be immediately emptied outside the tent to avoid it freezing. Pee bottles are labelled to avoid filling them

with water or a fizzy drink during the day!

I remember a well known correspondent who was covering the expedition for a national paper, peeing into an empty biscuit tin at Camp 3 (he didn't have a bottle). To compound his unpopularity he thawed it out over a stove the next day. Damart Long Johns for example are always popular for high altitude and Amazonian bashing. These sexy, navy blue tights were the next best thing to the bare skin of Amerindian porters, who glide fully laden through the rain forest as if turbo charged. Incidentally, I also obtained these garments each Christmas from the manufactures for our Rescue Team. On one occasion, when requesting our annual supply, I asked for the usual ''black variety''. In due course they arrived, with a Yuletide note from the managing director, wishing us well and pointing out: '' in fact we don't manufacture ''black'' Long Johns, despite the colour they may appear after use on rescues.''

Black vests were the in thing in New Zealand and the Australian bush and there was an old antipodean adage: ''Beware of barbers in black vests - they're sheep shearers''.

Long Johns have been misrepresented in many ways. The late Dr Tom Patey once accused me of using my Long Johns as an abseil sling when balling off a route. In fact, it was my string vest. It's now some time since Scottish bread snappers were sewn into their combinations for winter. I wouldn't have voted to have been at the ''steamie'' for their spring wash!