I thought that I was walking along a French Grande Randonnée, or long-distance footpath. But, securely locked gates blocked my way. Beyond them lay a pall of greasy grey smoke, and an overpowering stench; a nearby sign announced the times when one was permitted to deposit one's ordures.

So, I re-traced my steps for over a kilometre till I picked up my route again. Back at the cross-roads where I'd gone wrong, I found the clues I'd missed.

A sign, hidden behind the leaves of an elder tree, showed where I should have changed direction. A symbol indicating the wrong route was painted on a telegraph pole, to which the Télécom people had recently applied a coat of creosote. It was still visible ... but only if you looked really hard.

Usually, there are markings confirming you're on the right route. There weren't any on this occasion, because there just wasn't anything to paint them on for nearly half a kilometre down the road.

This is how the system should work. Two bars are painted on trees, rocks, signs, posts and sundry other wayside objects along the route. Four bars with an arrow mean a change of direction. A cross means you've taken the wrong path.

We used to joke that you shouldn't park your car by a GR for more than an hour. If you did, you'd find a balise, or way-mark painted on it when you returned. I once found a dilapidated Renault 4 in a Normandy farm-yard so decorated. But, a small tree was growing through its sun-roof, so it was probably regarded as a permanent fixture.

The colour of the balisage depends upon the kind of path you're walking. GR's are marked with red and white bars. GR's de Pays are regional routes, usually circular, and usually taking 2-3 days to complete. These are marked with red and yellow bars.

If your idea of a heavy load is a baguette, some cheese, a bottle of water and a camera, then the PR, or Petite Randonnée may be for you. It should take no more than a good day, and bring you back where you started.

PR's are marked with single bars ... usually yellow, although other colours are sometimes used. And, as with all things French, there are frequently regional variations.

If you want to walk the PR's, it's best to buy a guide-book. That will enable you to crack the local code.

In practice, the sport is not so much the walking. It's about seeking out, and finding the balises you're supposed to be following! On many occasions, I've suspected I'm on the wrong path because I haven't seen one for a while. Then, an unmistakable feature on the map, or even a splash of paint on a wall confirms I was right, after all!

Sometimes, at a junction, I've reasoned that the way to go is the one without the cross on it. Sometimes, I've seen four bars without an arrow, and been left to guess which way the direction changes. And, often, the markings simply peter out. A walker has three options; use his instincts, toss a coin ... or, dare I suggest, try reading the map!

But, we can't be too uncharitable about this situation. The extensive way-marking is mostly done by unpaid volunteers. I do some of this kind of work at home in Britain ... and I'd much prefer our method, where I carry around a hammer, some nails and a pocketful of plastic way-marks, rather than two pots of paint and brushes.

I suspect the reason for the condition of most French way-marking I've found so far is this. I prefer the less populous paths, and here, the Man with the Paint-pot probably doesn't get around so often.

His work may weather with time ... although plastic markers, called jalons are beginning to be used. More usually, the tree on which he puts his mark may be cut down or fall over. Sometimes, the sign or telegraph pole he's marked is repainted or replaced. Mostly, the culprit is Nature, covering the balise with moss, ivy or foliage.

I'm not knocking the system, though; far from it! I think that having to expend a little effort looking for the balises, rather than simply following them, adds a great deal to the character and fun of walking French footpaths.

I've learnt my lesson. I've got into the habit of stopping at every junction I come to. I have a really good look around before proceeding further. I'm frequently surprised at the things I see that I might otherwise have missed. Sometimes, I even find the balise I was looking for!