AS A wide-eyed young lad abroad for the first time, I was struck by three things when we landed in France on a school trip.

The policemen wore guns on their hips as casually as if they were bunches of keys, the metal scratched and battered as if they got plenty of use.

Kelloggs corn flakes and Colgate toothpaste were on sale in French shops. How could they be selling English breakfast cereal when I was expecting Le Crunchies? But then I had no idea about international corporations or worldwide marketing.

The third thing was the smells. On that trip, I shared a lift with three French men jabbering away in this language I had been learning in class and I couldn't follow a word. I stood there looking up into their large, hairy nostrils and was overcome by the whiff of garlic and Gaulloise.

In those days, no self-respecting English household would countenance garlic in the kitchen. So the secondhand pong in that lift nearly knocked me over.

To me, smell is the most evocative of all our senses. It's a sort of scents and sensibility. One whiff and it can transport you back in time to the very moment you first inhaled a certain aroma.

Neither sight nor sound is half as effective in provoking memory flashbacks so vividly.

I need only get one twitching nostrilful of cigar smoke and it takes me back to Sunday nights when my gramps had his friends round for a game of cribbage. I would stand behind him and try to inhale his expelled cigar smoke; then he would let me suck the froth from his Mackeson stout. It tasted awful, but then smoking a cigar is never as pleasant as smelling it in the air.

Fifty years on, one sniff of cigar smoke has me remembering Nick the Greek profaning in his strange accent at a bad hand of cards, gramps' bald head wrinkling as he laughed, and the red tasselled table cloth they dealt their hands on.

Trouble is, I once read that are smells are particulate. Which means to the uninitiated that each smell is made up of tiny particles of the substance which caused it.

Now that's fine when you are inhaling the mouth-watering smell of percolating coffee or a sizzling roast. But when you are driving past Naburn Sewage Works - you never get the car windows shut in time, do you? - or get hit with the liver-and-onions stench of someone's unwashed armpits or the fine aroma of stinky socks, it makes you wonder what you are breathing in.

Schools have a smell all of their own. Whether it's the pong of hundreds of little bodies in confinement, the dusty smell of ageing books, or the musty smell of sports kit left too long and damp in a locker, they never fail to take me back.

One of the sweetest smells of nostalgia was the era of steam trains. As kids we used to stand at the top of a footbridge over a railway line to disappear in the thick steam as a loco passed beneath, and the smell of that vapour was incredible. There's nothing like it these days.

Well, actually there is: perfume, women's perfume. Walk down the street and catch a provocative whiff of a certain perfume and it brings back blinding nostalgia flashes of a particular girlfriend, a good night or waking up sick and hungover reeking of a certain scent. To this day, I feel ill whenever I smell the lovely perfume Clinique, for just that reason.

Different smells have a profound effect on our senses. The disturbing, distinctive smell of old people's homes reminds you forcibly of the mortality of a loved one or even yourself; the smell of Johnson's baby powder is beautiful beyond compare because it is associated with smooth, unwrinkled skin and a full life ahead.

Depressed yet? No need, the world is full of happy smells. Get off an aeroplane in a hot country and the smell tells you better than anything - except cocoa butter sun oil - that your holidays are starting.

Peel a tangerine and it brings back the scent of Christmases past.

Hmmm. What smells turn you on?

Updated: 09:40 Tuesday, July 05, 2005