Before we set out, I had vaguely registered the fact that, although France's population is much the same as that of England, its land area is four times greater - and suddenly, in the hills above the valley of the Lot, we found vivid proof of the statistics.
Here was open space such as we can only dream about at home. For kilometre after kilometre, the woods and fields rolled on: huge forests of sweet chestnut and oak tumbled into the valleys; small grass meadows lay knee- deep in wild flowers; handsome stone farmhouses lurked in sheltered corners, and the occasional fortified medieval village stood perched on a hilltop.
If one car passed us every 10 minutes, we felt aggrieved, and after our picnic lunches we sank down for siestas in the deep herbage by the roadside. For long periods, the loudest noises were the clonk of cow-bells, the zing of cicadas and the whistling of buzzards.
Buzzards ahead of us, buzzards behind, buzzards above and buzzards below: almost always several of the big brown hawks were airborne, and their ubiquity epitomised the wildness of our surroundings. More and more I got the feeling that this was what England must have been like 100 years ago. Among the eyebright and speedwell on road verges, wild strawberries were ripening. In the meadows, the grass was so lush that only the heads of lying cattle showed above it. Charollais, Limousins and a handsome local breed called Salers, with long horns and smooth, dark red coats, all looked as sleek as sleek could be. Free-range chickens wandered far and wide, and the occasional fields of rye were studded with gloriously deep blue corn-flowers.
There was never a sign of anything so crazy as set-aside, never a field with its verdure blasted to death by chemicals. Farmers wearing blue berets trundled about on small and ancient tractors, none of them fitted with the roll-bar obligatory in this country. If the locals were obeying any of the lunatic edicts of Brussels, they were showing little sign of it.
It was hard to equate this arcadian scene with the violent political aspects of French agriculture habitually reported in British newspapers: the blockades of main roads by infuriated farmers, the attacks on lorry- loads of British lamb. We seemed to be - indeed, were - in another country.
There was plenty of time to reflect on other minor puzzles. Everyone I questioned confirmed that the woods were heaving with game: roe deer, wild boar, hares, rabbits, pheasants. Yet in the course of 200 miles we saw extraordinarily little wildlife: one rabbit, a few lizards, a mouse or two and a squashed grass-snake. Among birds, the most notable absentees were wood pigeons. In British farmland we would have seen dozens. Here there seemed to be none. In England we would have come across magpies by the hundred. In the Lot we saw three only.
Notices proclaiming that the collection of wild mushrooms was absolument interdit suggested that in autumn the woods must be full of delicious chanterelles and ceps; but wherever we went, chestnuts remained the dominant theme.
Until that trip I had always thought of sweet chestnuts as essentially park trees, growing in solitary splendour. Here they were massed in myriads, whole forests of them, and the sunlight filtering through their spiked leaves was entrancing.
Not for nothing is the whole area known as La Chataigneraie - the chestnut plantation. Nuts had found their way into everything: puddings, dessert wine, liqueurs, and even the honey which we bought in a village clinging to the side of a hill. The dark, gluey syrup tasted like a melt-down of marrons glaces.
I know that climate plays a big part in all this - that the Lot is several hundred miles south of London and a good deal warmer. Yet it was the space and the lack of people, more than the temperature, that captured my imagination. In our overcrowded islands, only barren moors and mountains offer comparable escape.
Perhaps if global warming continues, we may yet have the last laugh: if the Lot turns to desert, and the Scottish Highlands become farmland, roles may be reversed. For the time being, however, I cannot help feeling jealous of those green hills in the south.