It really is the most crushing disappointment to stay at the former chateau of the Marquis de Sade and not even get a lumpy bed.

Never mind that I was so tired they could have put hot coals in the mattress and I wouldn’t have noticed. I just wanted a whisper of the old ways, a snap of the whip calling us to dinner, that would do.

Except there was no dinner. The kitchen was closed. That’s the spirit, Monsieur Le Marquis, I knew you wouldn’t let me down.

In fairness to the fabulous Chateau Mazan, we should have known the kitchen was fermé that night. This information and a whole lot more had already been provided in a truly impressive bible of maps and need-to-knows for our glorious walking holiday in Northern Provence.

Glorious but testing in all sorts of ways. This particular walk – where you put in the miles and your bags are delivered each night to your next billet – was not for feeble or faint-hearts.

Whether it was for hearts which had been surgically by-passed is a question we will come to.

I’ve taken a walking holiday with the Australian journalist and author (and Mildrover editor) Jimmy Thomson every year since I can’t remember when. Two ancient hacks, we have bickered our way across the world, two weeks at a time, with just about enough new stories each year to light the way – the hope being that as we grow more forgetful, we need no longer preface every yarn with “I’ve probably told you this before but…”.

So anyway, the dog had been following us for about three miles when this year’s bickering started. The mutt was a black labrador, energy to squander, bursting with playfulness, trying hard to include us in his doggy schemes.

We didn’t have energy to burn or certainly not to waste, so were happy to let the dog get on with it. Until Jimmy said we should phone the dog’s owner – the hound had been following us for too long now. What if he was still with us when we got to Le Barroux?

Well, if he was, I grumped, he could find his own way home, couldn’t he? He’s a Provencal dog, a local, he knows his way around. By now, the dog was dozing on a rock. So Jimmy got the owner’s number from the dog collar and I reluctantly agreed to call him.

To my annoyance, the owner, whose English was worse than our French – no small achievement – couldn’t thank us enough. Stay there, I’m coming. Where are you?

Er, We hadn’t a clue. Tell him a road with stones. Stones? Yes, a stony road…with fields on either side. He can’t miss it. Strangely, this wasn’t enough. And by now, the mutt had sensed his maitre’s anxious presence on the dog and bone. So naturally he started howling. Jimmy did the only thing a 70-year-old man with a heart condition could do: he started howling too.

Which freaked out the Frenchman on the phone. My dog, is he alright? Owwwwww! Yeah he’s fine, really, my dog does the same when he’s happy (or when he listens to Astral Weeks).

It was clear we were now not the only ones in Provence with a heart condition. But then – and I am not making this up – we somehow figured out where we were by turning the Ordnance Survey Map the right way up and an extremely grateful farmer came to pick up his dog, itself now panting and shiny-eyed with pleasure at the morning’s chaos.

We kept getting lost. Jimmy is a brilliant map reader but we still kept getting lost. This walk is designated Medium-hard and it doesn’t just mean steep hills. It also means not so steep hills. It means long comfortable stretches of sun dappled country paths, buzzing with contented…hang on, shouldn’t we have seen a signpost by now? So you need to focus but I was glad we didn’t. And speak it softly but they have mobile phones in Provence and taxis and everything.

But yes, there was a lot of walking uphill. Occasionally, there was lung-bursting scrambling over rocks and scree to emerge from Provencal pine forests to what we felt must be the top of the world.

But it was nowhere near the top of the world. Because then you look up to see Mont Ventoux. The Beast of Provence. It follows you everywhere, its brooding presence reminding you daily who’s the daddy.

Apparently when the Mistral blows, winds can gust so hard they close the road over the top. Shorn of trees and vegetation, the limestone summit gives the bald mountain a bleak and slightly spooky look.

By reputation, it is one of the most brutal and punishing stages of the Tour de France, almost as though they had consulted Le Marquis.

They can keep it. For us, the Dentelles de Montmiral would do just fine. Dedicated walking paths that snake through a paradise of vineyards and olive groves, before rising through woods to the more challenging saw-toothed peaks, this was a real test for cardiac meddling. Goodness, it was exhilarating.

If I sound like I took our heart conditions lightly, I’m bluffing. Life is more precious now than it ever was. So climbing up some of the steeper paths, there was a lot of stopping, getting our breath back, taking all the time we needed to figure out how we ever got this stupid. And then you look around.

Gaze down from a limestone peak over the lush spread of Provence below and you realise where God’s country truly lies.

And then there was the food. Oh Lord, the food. Breakfast tables bow-legged with the weight of warm pastries and preserves, eggs and cold cuts, fresh fruit salads – no, that really won’t do. My apologies: every time I try and write about food, the confection comes out like a first round loser in a TV cookery show. Undercooked or overbaked, instead of an experience, I just seem to end up listing ingredients.

An early life of cigarettes, booze and print journalism – the first two thankfully behind me – seems to have wrecked, not just my taste buds but my ability to capture the emotional experience of great food.

But I can at least say this: fabulous breakfasts fortified us for the day ahead and delicious gourmet dinners replaced necessary calories left behind on the road.

Even the Saigon restaurant round the corner from the (fermé) dining room of the Chateau Mazan worked up the most delicious and generous supper.

For us this was not necessarily a good thing. I’m 75 and Jimmy only a few years younger. Recently, I had a quadruple heart bypass, Jimmy a paltry brace. Just before we came out, a blood test showed I was pre- diabetic. Carbohydrates were not my friend. And yet without them how could I possibly take this trip on? For pity’s sake, even the clouds looked like souffles.

So I did not stint. Only once whilst patting my heart ruefully, did I turn down an especially creamy- looking plate of dauphinoise potatoes. The waiter looked so hurt I ordered pavlova for dessert. What can you do?

It may be that to make up for my diet in France, there will be a lot of thin gruel ahead. These are my just desserts. The food I ate in Provence threatened my health far more than any walking. But I burned more calories than I took in because incredibly, it seemed to me, at the end of the trip I had still lost weight.

Kieran Prendiville & Jimmy Thomson hiked as guests of On Foot Holidays (www.onfootholidays.co.uk) travelling to Avignon at their own expense.

Kieran Prendiville created and wrote the BBC TV series Ballykissangel  and Roughnecks and won a Bafta for his drama Care. A former Fleet Street news reporter, he was also a presenter on That’s Life, Tomorrow’s World, Nationwide & Grandstand.

Jimmy Thomson has written three novels, 12 non-fiction books, and created or co-created three Australian TV drama series. His new novel Mole Creek (writing as James Dunbar) was be published on August 1.