When the knees began to give way, Sarah Shuckburgh hit upon an idea to save her walking trip.

On Day Two of our holiday, we decided to look for flat walks. This decision arose from two disturbing discoveries made on Day One.

It had seemed such a good idea: a week hiking in the Haute Savoie. Gila and I - friends of 30 years' standing - planned to combine long walks with long chats, returning home to our families astonishingly toned, fit, slim and healthy, with flawless complexions, and all life's problems solved.

We woke on our first day in Thollon to find the Alps obscured by fog, but, after consulting the guidebook, decided to stroll to the village of Meillerie, on the banks of Lake Geneva. An encouraging signpost read "Meillerie 60 minutes", and we set off at a leisurely pace. "We'll have elevenses at the lake and be back in time for lunch," we agreed.

We ambled down rutted lanes beneath leafy canopies, and sauntered past quaint gingerbread farmhouses with carved balconies and painted shutters. After half an hour, we passed a second sign, which read, to our surprise, "Meillerie 50 minutes". We seemed to be making very slow progress.

Now the path dwindled and narrowed, and we found ourselves on an almost vertical slope, battling through
tangled undergrowth, wading across waterfalls, stumbling over roots, clambering round fallen tree trunks, and
skidding on loose pebbles. And this is when we made our first Disturbing Discovery - that I, or rather my knees, hate walking downhill.

Through the mist we caught occasional glimpses of the sunlit lake, glittering miles below us, and heard distant bells chiming the hours. At last, as one o'clock struck, the undergrowth parted to reveal a flight of medieval stone steps and we staggered to the edge of the rippling lake.

I can vouch that Meillerie is a lovely place, with a 13th-century church and fishing nets hung to dry among the geraniums. But what superfit Alpine commando clocked up that timing? The downhill walk took us not one hour, but three, and left us with a serious dilemma. Over lunch in a lakeside café, we discussed our desperate situation. Should we, or shouldn't we, order a taxi to take us home by road - a circuitous route of 20 miles?

Finally, puritan ethic, pride and parsimony persuaded us to walk. As we struggled upwards - past a sign saying "Thollon 1h 30m" - gone was all chatter about friends and family. Now our only topic of conversation was whether, if one of us collapsed, the survivor should go back down for help, or head on up. Meillerie church chimed pityingly as we slithered up the muddy mountain.

The ascent took five hours, during which we made our second Disturbing Discovery - that Gila is hopeless at walking uphill. Next day at the alimentation, the shopkeeper confided that nobody with any sense ventured down that path to Meillerie. Once a family had set off on bikes, but had jettisoned them in despair. "The bicycles are down there, somewhere in the undergrowth, to this very day," she shrugged. And so it was, that with one of us useless going downhill, and the other useless going up, we hit on the brilliant idea of Flat Walks.

Thollon - a thriving ski resort in winter - is almost empty in the summer but, luckily for us, the cable car was still
manned. After the operative had finished his cigarette, the machinery would creak into action, wafting us up the north face of les Mémises to gently rolling Alpine meadows at the top. From here, we could strike out in any direction with minimal gradients.

We settled into a pleasant routine. Over breakfast, we'd comment hopefully on the weather. Then we visited the alimentation to buy a picnic of dimpled apples, mouldy plums, soggy lettuce and dried bananas (well past their sell-by date), while the shopkeeper lectured us on the folly of setting foot out of doors in this "mauvais temps". At the telecabine each morning, the operative would warn us of the "risque d'orage", as he smoked another Gitane.

Up on the mountain, we became expert at finding flat walks. Cross-country ski routes were best - wide, grassy tracks through fir trees and along ridges. Signs saying "balcon" also lifted our spirits - foretelling an easy stride under the lee of a mountain, with spectacular views. Thrillingly, after our humiliating progress on Day One, our pace on these horizontal paths matched the Alpine Commando's timing. It felt marvellous to be three times as fit as a few days before.

The weather forecasts were uncannily accurate, and we often plodded through brouillard, bruine, nuage and grisailles. We ate lunch perched on grassy ledges, as banks of mist wafted past us, our soggy greengages and bruised grapes like nectar. In periods of sunshine, we were treated to sightings of the crenellated Dents d'Oche, or a slice of the shimmering Lake Geneva with Lausanne on its far bank. The flowers did not seem to mind the unseasonal weather - delicate harebells nestled in the dewy grass, with blue and yellow autumn crocus and vivid gentians. Even better, wild strawberries, myrtleberries, and wonderful wild raspberries glistened in every hedgerow, ripe and exquisitely sweet.

We hardly passed a soul all week. When we did, every enquiry about gradients brought us new words to dread - escarpe, accidente, pentu, raide, une escalade difficile or pic. We longed to hear the comforting plat, horizontal, en pente douce and au même niveau.

At teatime each day, Gila and I rode down in the cable car (no charge, but more alarming than the ride up, lurching down the 3,000ft cliff), and then lingered in the café over mugs of hot chocolate. Each evening, we dined on local specialities, such as la véritable raclette - an eccentric mountain dish of melted cheese, potatoes, gherkins, pickled onions and salami - for which a two-bar electric fire arrived on our table to scorch a semi-circular hunk of cheese, clamped to a wrought-iron bracket.

On our last day, we attempted our longest walk yet. We ascended in the telecabine, and marched off. Six days of chattering had exhausted our gossip, and we had successfully sorted out each other's problems, so we were striding along in companionable silence when the path abruptly stopped at a vertiginous cliff.

Nervously, I shuffled towards the edge, peeped over and gasped. Jagged rocks 50 feet below signalled certain death. I stepped back and Gila glared at me accusingly. I have always prided myself on my map-reading. I know how to use a compass, and I hardly ever have to turn the map round to fathom out which way I'm going. How could I have missed this?

I put on my glasses and peered at the map again. And there it was - inscribed across a dense cluster of hitherto unnoticed contour lines - one dreadful word, échelle. "It's very small print," I blathered. "Anyway, would we have known what échelle meant?" Alas, Gila is well educated. "Une échelle, la scala - cognate with scale, escalator, stairs, ladder!" she pronounced.

We inched towards the precipice again. Rusty rungs, wet and gleaming, disappeared into the swirling mist far beneath us. I felt giddy just looking at them. "I don't think I can do it," I gulped. "Nor can I," mumbled Gila, retreating towards
firmer ground.

The detour, meticulously planned and double-checked with our glasses on, successfully avoided all densely clustered contour lines, and instead featured many zigzags, an escarpment, two cols, a balcon, and five gentle inclines. After two hours, we found ourselves near the ladder again, but this time safely at the bottom. As we ate our baguette and squashed tomatoes, we spied four ancient hikers approaching, their white heads bobbing above the bracken.

"Game old things," Gila whispered.

"Bonjour, mesdames," I ventured in my schoolgirl French, as they pounded up to us. "Avez-vous vu cette échelle terrible?" The old ladies' shorts displayed sinewy calves, which disappeared into canvas gaiters, their necks were festooned with binoculars and maps, and an impressive ski pole dangled from each sweat-banded wrist.

"Mais oui, mesdames! Bien sur! But yes, of course, we have just come down the ladder," called the old dears, as they stormed past. "It's no problem." With wry grins, Gila and I heaved ourselves to our feet, and stepped out on the last leg of our walk. As if by magic, the fog suddenly lifted, and to our astonishment we found ourselves standing in brilliant sunshine, beneath a clear blue sky. All around us, a breathtaking panorama emerged, of snowy peaks, steep, thickly forested mountainsides, flower-strewn meadows, and, far below, the sparkling lake, dotted with tiny white sails. Cowbells tinkled merrily, and a warm breeze brushed our cheeks.

"This is a nice flat bit," I said. "Let's come here again.''

First published by the Telegraph
©SarahShuckburgh