Everything is green in Devon – except the azure sky

'Are there any smoked salmon in the lake, Daddy?" Shhhh! This is my six-year old son, Edmund, giving away our secret – that we are just another bunch of townies on a trip to the countryside. But we've a special reason not to seem like greenhorns on this first day of our "green holiday".

This isn't one of those "let's buy some organic asparagus in M&S" gestures. We have decided to do the "full green" – staying on an organic farm in a remote but beautiful part of the West Country, eating as sustainably as possible, leaving the car at home and travelling by public transport.

The last time holidaymakers in Britain regularly did this was in the 1950s, before agribusiness carved up the countryside and before the evil Dr Beeching closed the branch lines.

So here we are at Paddington, boarding the 10.05 to Barnstaple via Exeter – our coolbag packed with organic goodies. The train line from Barnstaple to our destination – Braunton, near Ilfracombe in North Devon – closed in 1966, but we are going to get as near as dammit by rail.

But what of Little Comfort Farm where we are to stay? Does it just mean little and comfy? Or will it be more like Stella Gibbons's scary version from her novel Cold Comfort Farm? Any doubts are dispelled at Barnstaple station, where we are welcomed by cheery Jackie Milsom, the very image of the jolly farmer's wife. An unlikely eco-warrior she, we think, but soon she is telling us passionately about her organic farming vision. The farm is green in every sense of the word. Tucked away in solitude in a wooded valley, the only non-green colour around here is the deep azure of the sky.

We tuck voraciously into Jackie's home-made scones with local organic clotted cream and home-made raspberry jam. Then husband Roger takes us for the evening round to feed the livestock. He explains that there are no pollutants on Little Comfort. All the fields are rotated in strict order, according to the rules of the Soil Association, with manure from the animals ploughed-in crops providing all the nutrients.

And it is buckets of organic maize and soya that we are delivering for supper to the 350 Black Rock chickens, 10 Devon Ruby cows, 50 breeding ewes, three breeding sows and Bertie, the Gloucester Old Spot boar, who is 16 stone, and highly fertile. (There are 10 week-old piglets. "Bertie helped himself," says Roger ruefully.)

Settling down for the night, to the sound of satisfied grunting from the two piggies in the barn outside our door, we reflect that on our first day, we have at least achieved an organic pass rate. And there's certainly no cold comfort here, sitting by the log fire in Granary Cottage tucking into Roger and Jackie's organically produced steaks.

Next day, the difficult bit starts. There's no problem trekking up the hill to collect the still-warm eggs for breakfast. But how are we going to get around without a car? But all good townies are never far from an OS map, and ours shows a pub in the village up the hill. So wellies on, we set off on foot. The agricultural workers of old thought nothing of walking 10 miles to work and back, we tell our boy.

Next day we get even bolder and take the bus to the beach at Ilfracombe, eight miles away. It is empty and the driver becomes our personal chauffeur into the centre of town. No parking worries here. Nor do we resort to artery-clogging fudge and cream-teas. We opt for freshly caught sardines on toast in Damien Hirst's quayside restaurant.

But don't get the idea that life is soft here. Jackie and Roger have to labour hard – the yield on organic farms is lower, the work tougher. Try growing all your own vegetables, making your own jam, honey and apple juice as well. The compensations for the Milsoms – and for us – lie in what the chef Heston Blumenthal calls "the morality of food production". As dusk settles we can just glimpse the farm's rare community of greater horseshoe bats. They flourish because of Roger's ban on chemicals.

As we prepare to go home, I calculate we will have travelled more than 400 miles by public transport and on foot, but only 20 by car and taxi. We have lived royally on the finest local produce. Have we helped save the planet? I don't know. But Edmund is making us vow to return – and we have discovered a new word. Like Roger and Jackie, we are committed "locovores" now.

COMPACT FACTS

How to get there

Little Comfort Farm (01271 812414; littlecomfortfarm.co.uk) offers five cottages for hire, sleeping from two to 10 people. Cottages start from £306 per week. Three-night breaks are also available from £282. Advance purchase rail fares from London to Barnstaple start at £12 single with First Great Western (08457 000125; firstgreatwestern.co.uk).