A Frenchman, an American and an Englishman went for a walk in Wales. The Frenchman was worried about the food. "What do they eat in Wales?" Hervé asked repeatedly. "Are you sure you can eat well in Wales?"

The American was worried about the weather. For many weeks beforehand, Mark checked the Welsh weather each day on the internet at his apartment in New York. At regular intervals, he sent an email to Hervé which said, in effect: "Oh my God. It is still raining."

The Englishman – me – was worried about everything. We had previously walked together in the Luberon hills and the Basque country in France (as related in The Independent Traveller last year, see independent.co.uk/threemen). It was my idea to take my French friend and my American friend to somewhere more exotic this year; to somewhere more challenging and risky.

"There is a part of Wales," I told them, poetically. "That is wild and beautiful with unspoiled estuaries and mountains sweeping down to the sea. As a child in the late 1950s and early 1960s, my father would take us there every summer holiday. On a fine day, there is no more beautiful walking country in the world..."

On a fine day.

Hervé and I set off by car from Paris. Mark flew overnight from New York. We picked him up at Heathrow and we drove to Dolgellau, southern Snowdonia, where we had booked rooms at the Royal Ship Hotel. We had planned four days of walking and eating: four days of truancy from our families for a trio of fiftysomethings.

My friend Hervé, 57, is a Parisian importer and exporter of high-quality, specialist paper. He is as international as a Frenchman can be but ultimately very French: ie very critical, especially of food. He has something of the comic manner, but a greatly improved version of the looks, of Jacques Tati.

My friend Mark, 55, has lived with bushmen and swum with sharks. He is 6ft 6in and absurdly handsome, a former accident and emergency doctor from Maryland. Think Indiana Jones meets Dr Kildare. He now invests in small companies with promising medical ideas. After six years in France, and a world tour, he lives once again in the United States.

Walking and eating together have exposed friendly cultural rifts. Mark believes Hervé is over-critical, especially of food. Hervé, without quite saying so, regards both his Anglo-Saxon companions as undiscriminating, especially when it comes to food.

On the whole, therefore, I was more worried about Hervé's views on the Welsh food than I was anxious about Mark's feelings about the Welsh weather. In the 1950s, it never rained in Wales.

Day one: rain in England; sunshine in the Welsh border country. Hervé telephones home and asks for emergency supplies of sun-cream. By the time we reach Dolgellau it is raining. Cader Idris, 2,900ft, our objective for the next day, is shrouded by a black, swirling cloud.

Hervé insists that we must attempt our first short walk before dinner. We drive to Morfa Mawddach, formerly Barmouth Junction. I spent many happy hours here as child watching the steam trains crossing the long, low, mostly wooden, railway bridge to Barmouth. In my memory, the panorama of the Mawddach estuary from the toll footpath alongside the track is the finest natural spectacle in the world.

The rain stops. The clouds lift, but not from Cader Idris. A dull, silver-coloured Arriva diesel train passes. We see a small part of the view.

Nevertheless, we return to the hotel very happy. Dinner is a triumph. The Welsh specialties include rack of Welsh lamb, cooked beautifully by the twentysomething chef, Simone, who comes from Bucharest. The meal is served with great aplomb and humour by her fiancé, Ioann, who also comes from Bucharest. The hotel is brilliant value, run with warmth and efficiency by a Lithuanian, Romanian, Canadian, Irish, English and Welsh staff.

We ask Ioann what he thinks the weather will be like tomorrow. "This is Wales," he says. "It will rain... wait a moment." He pops his head out of the door and comes back to us. "Yes, rain."

The next day it emerges that Ioann is wrong. It is not just raining but blowing a gale from the Irish Sea. We decide to delay our attempt on Cader Idris, still hidden by black, swirling cloud.

We visit Harlech Castle and buy some brown bread for a picnic lunch. The bakery does not have a slicing machine. The baker's husband rough-hews our loaf into uneven lumps. Hervé is suspicious. What kind of bakery doesn't have a slicing machine?

The rain eases but not the gale. We go for a walk on Harlech beach: six miles of sand. We cross the dunes in a severe sand-storm. On the beach, the seagulls are flying backwards. We drive inland to the Rhinog mountains, one of the wildest parts of the British isles. Beside the lake at the end of the long, narrow road to Cwm Bychan, we eat our sandwiches in the car. The bread is a triumph, among the finest loaves the two Parisians and one ex-Parisian have ever eaten. Wales one, France nil.

In dull, windy weather, but no rain, we make the ascent of the Roman Steps, an extraordinary stairway to the heavens built 800 years ago. But why are there no proper trail-markers? In France, there are colourful signs painted on trees and rocks. Here, we get lost a couple of times in the mist.

Dinner is at the Royal Ship in Dolgellau, again. The Welsh rack of lamb is served by Simone from Bucharest, again. It is excellent, again.

Day three: rain in the morning; sun in the afternoon. Unfortunately, we walk in the morning. We drive 30 miles north to the beautiful village of Beddgelert, at the foot of Snowdon. The rain hits as we are climbing up through an old copper mine, close to the reputed birthplace of the wizard Merlin. The walk ends with a spectacular river-side path through the Aberglaslyn pass. We arrive back at the car soaked to the skin.

For dinner, we make an expedition to the George III Hotel at Penmaenpool, beside the Mawddach Estuary. I remember the George III when it was just a pub beside a railway line. A few yards away was a small locomotive shed, where two steam locomotives would simmer between trips up the valley to Ruabon and Chester. The old station building is now part of the hotel.

Hervé points out that the food he has eaten so far is Romanian, not Welsh. So this is the real test. He chooses bream. Mark and I eat steak. "Gentlemen," Hervé says. "I have to tell you that this food is fantastic." He goes into the kitchen, uninvited, to say "bravo" to the chef.

Our final day is the big one. We decide to climb Cader Idris, clouds and all. I want to approach the mountain from the south, using the same, gentle route that I took when I reached the peak with my father and brother on a warm, cloudless day in August 1963. We stroll up the first three or four miles of shepherd's tracks in bright sunshine, with spectacular views over the emerald slopes of the mountains to the south. Cader Idris performs a kind of striptease, beckoning us on by allowing its dark, grey robes to slide from its shoulders. The sharp peak is briefly revealed and then covered up again.

We stagger up to the final ridge, 800ft below the summit. The weather does not deteriorate; it collapses. It explodes. As we attempt to picnic, we are struck by gales, hale and driving rain. Hervé, courageously, starts on the path towards the peak. Mark and I call him back from the mist and insist on going back down to the car. The superior pluck of the French? Maybe. But Hervé is the only one of us wearing waterproof trousers.

By the time we've driven to Dolgellau and had a shower, the sun is shining. The peak of Cader Idris is clear. We drive up to Bala so that I can show my visitors a little of inland Wales. The woman in the gift shop gives Hervé 20 per cent off three pairs of Welsh socks. Since the Inuit had hundreds of words for snow, I asked her, did the Welsh language have more than one word for rain? "No," she says, brightly. "Just glaw." She paused. "Glaw, glaw, glaw ..."

That night Hervé insists on trying the fish, chips and mushy peas in the hotel bar. A mistake.

Conclusion? Wales is fantastic. We had a great time. Pity about the weather. Next time, bring waterproof trousers. And underpants.

John Lichfield is The Independent's Paris Correspondent

Traveller's Guide

Getting there

The closest mainline rail stations to Dolgellau are Machynlleth and Morfa Mawddach. The line is operated by Arriva Trains Wales (08457 484950; nationalrail.co.uk).

Staying there

Royal Ship Hotel, Queens Square, Dolgellau, Gwynedd (01341 422209; royalshiphotel.co.uk). B&B starts at £70.

Eating & drinking there

George III Hotel, Penmaenpool, Dolgellau (01341 422525; georgethethird.co.uk).

Visiting there

Harlech Castle, Harlech (01766 780552).

More information

Snowdonia National Park Information Centre, Dolgellau (01341 422888; eryri-npa.co.uk); Visit Wales: 08708 300 306; visitwales.co.uk.