Rory Knight Bruce: A river runs through – and what a majestic history it has

Cornwall and Devon should celebrate what they share, such as the Tamar

(rex)

It doesn't take that much to needle the Cornish, and David Cameron's comments that the "Tamar is not the Amazon" touched a nerve. He was speaking last week about proposed parliamentary boundary changes that might create a new West Country constituency straddling Devon and Cornwall.

The would-be MP who takes this on would be brave indeed, for well before Trelawney raised his rebellious 10,000 Cornishmen, the two counties have been worlds apart. It is not simply a matter of geography but of economy. Devon has always been a rather sleepy but confident county. Cornwall, by contrast, has suffered the devastating loss of the mining industry and, despite millions of EU money, can resemble a Sheffield steelworks where the sparks have long been extinguished. Indeed, Sheffield has been described as "an ugly painting in a beautiful frame," but it is a saying which holds true for Cornwall. Anyone who has been to Camborne on a November night will get the picture.

There have been poetic stabs at the defence of both counties. Cornwall had, as its adopted son, the late Poet Laureate, Sir John Betjeman. Devon, for many years, harboured Ted Hughes. They took their loyalty to the grave, buried in their respective counties. David Cameron would have done well to choose his words as carefully as they.

To members of the Kernow (Cornwall) branch of the Celtic League or the Keep Cornwall Whole group, both of which are mainly composed of "emmets", or incomers, Cornwall is not a county but a country. While it may not be the Amazon, the Tamar, which was fixed as the border of Cornwall by King Athelstan in the year 936, runs from less than four miles from the north coast 50 miles to the south. Cornwall is very nearly an island.

But what a border the Tamar is. Not for nothing is its valley classified as an Area of Outstanding Natural Beauty. It takes in farmland, granite landscape, salt marsh and ancient oak woodland. In its stately initial progress, the river's course is direct. But once past Launceston, about halfway on its journey south, it takes its time and explores its surroundings. It is crossed by some of the finest of medieval stone arch bridges, such as the wonderful Greystone Bridge at Dunterton, built in 1437. A few miles downstream, after the river has begun to meander markedly, almost reluctant to reach the sea, is the equally pauseworthy, and equally old, masonry arch bridge at Horsebridge, with the 15th-century Royal Inn nearby.

Then comes Gunnislake (whose bridge, a mere 500 years old, was the first in Cornwall to be built using large quantities of granite), where the Tamar becomes tidal. Here begin the mudflats, with their wading birds and the distant whiff of the sea. Then on it goes, passing the old copper quay at Morwellham, once the busiest port in Devon and Cornwall and on towards Saltash, with Brunel's epic railway bridge, Plymouth and the sea.

Cornish folklore has it that the devil never bothered crossing the Tamar into Cornwall, believing that were he to do so he would be used as filling in a pasty. Superstition lives on, but so do more perceptible political differences. On the Devon side, with its lush pastures, Ambrosia milk factory and celebrated Arundell Arms fishing inn, the mood is, largely speaking, conservative. Once you cross the water, you reach Saltash and a more liberal/independent hue.

There comes a point, though, when differences, imagined or real, become nothing more than parochial point-scoring. Both sides of the river, for example, rely on Plymouth for work. So what we should be doing, and here I speak as a native Devonian who sends his family on holiday every year to Cornwall, is celebrating the differences between our two counties.

The Cornish still have village galas where young girls dress up as carnival queens: Devon has Morris dancing. Cornwall has "emmets" or "janners": Devon simply calls them people who have retired to the coast to live out their well-earned retirement. Cornwall has surfing: Devon has stairlifts. True, hours may still be devoted to establishing who invented the pasty and who the cream tea, but there are already examples of cultural fusion with no dilution of identity.

Formed in 1967, the Devon and Cornwall Constabulary has never seen a felon set free on the Tamar bridge because he came from one or the other county. It has been a sensible deployment of resources. More Devonians holiday in Cornwall than the other way round, and not just because they can afford it. Cornwall has much to offer, with its rugged waves and landscapes, its rich history of piracy and the legacy of Daphne du Maurier.

Devonians, being of a more mild-mannered disposition and having no desire to declare themselves independent of anyone, will, I suspect, greet the boundary changes with their customary laissez-faire attitude. So far, most of the upheaval at David Cameron's remarks have come from separatist groups in Cornwall. Three Cornish mayors and several town criers have worked themselves into a lather to condemn him. A Cornish delegation opposed to the fusion has already met Nick Clegg. The mayor of Saltash, Adam Killeya, says that in Cornwall "the vibe is different", and is planning a campaign to sail boats across the Tamar in protest.

The vibe is certainly different, and that is what makes Cornwall special. Anyone attending this year's Port Eliot Festival on the eccentric Earl of St Germans's 6,000-acre estate will have experienced that. Cornwall still has an innocently feudal air which it could do well to share with its more democratic Devonian counterparts.

At the Rod & Line in Tideford, Cornwall, border terriers loll on benches, barmaids pull foaming pints, and several of the regulars still look like David Essex done up as a brigand. In Devon, the atmosphere at the Arundell Arms in Lifton could not be more different. Gents in tweeds are taking their ease and doing a spot of fishing. "When people come here from Cornwall, they talk about coming abroad," the hotel proprietor told me recently. What, no passport?

Parochialism is the enemy of democracy. When Scotland was clamouring for North Sea oil revenues in the late 1970s, I remember visiting Aberdeen and seeing a car bumper-sticker declaring: "It's Aberdeen's oil."

Any boundary change is going to upset some people. I live in a new constituency, Central Devon, and have precious little in common with far-flung constituents in Tavistock. But I accept that we are all Devonians. Similarly, if I were paired with Cornwall, I should feel that we are all from the West Country.

It is completely disingenuous of Mebyon Kernow (The Party for Cornwall) or any of the separatists groups to think that whoever is elected as MP for the newly fused constituency will not represent the varied interests of all constituents. And if it is to be the Conservatives' Gary Streeter, as it may well be, he should now be girding his loins and making himself known in Saltash or the finer clubs of Plymouth's Union Street.

Those opposing the new constituency should stop throwing up historical barriers to what should be seen as welcome progress and a reduction in parliamentary costs. They should, in Cornwall, stop looking to the EU for grants and, instead, be more open to what is happening nearer to home.

No doubt, when Mayor Killeya is bobbing about in the Tamar or tying himself to Brunel's bridge, he will claim that Cornwall invented the pasty. To which I can only respond: it was Devon that gave the world the cream tea, despite Cornwall's best efforts to prove otherwise.