The heat fills the Provençal landscape. It is a tangible thing that sets the distant rocky ridge shimmering, across a deep valley from the terrace of the Château de Gourdon, high in the hills above Grasse. Inside the seventeenth century castle is a fabulous private collection of art deco treasures. Room after room pay homage to the greats of French design of the thirties to fifties: not just a Le Corbusier chair but the Le Corbusier chair: the original factory prototype. The dressing table Eileen Gray made for her own use; astonishing decorated lacquer furniture by Jean Dunand.

On the château's 'Terrasse d'Honneur' lines of curving and swelling box seem to jostle one another. Their soft, rich greenness is a perfect contrast to the dazzling brightness of the limestone walls. Across the gardens and at a lower level, a Vivaldi recorder concerto sounds out from beside a large pool, just visible behind tall cypresses. Distant shouts from children playing by the water, as a gardener with a ponytail lackadaisically pulls weeds from a flower bed. From a little seat set into the wall I can look down on a private terrace. At the end of the terrace is a belvedere giving views on to the steep rocky valley below. On the stone table inside the belvedere there is water. Two youngish men sit at the table. One is tall, with longish dark hair, dressed all in white, the other shorter with light brown hair. In the sultry afternoon heat, a word or two of their gentle conversation drifts towards me.

When the castle visit is over, I sit for a while on the low wall of the roadway that leads down to the village. The two young men appear outside high double gates which hide the castle's private gardens. The taller man has aquiline features, his complexion is clear and pale, his hair quite black; his friend has a rounder, more sunburnt face. They are still chatting. Both have an almost aristocratic air.

Suddenly the taller man seems to catch sight of someone in my direction. He walks purposefully towards me - but stops halfway across the roadway beside a short and frail-looking woman with ginger-coloured hair. He gracefully kisses her on both cheeks. She seems pleasantly surprised at this unexpected compliment. The old lady and young man exchange a few words and he returns to his friend at the garden gate of the castle.

The two of them now stand for a while, until I am certain the taller of the pair is looking directly towards me for a second time - and in that moment a look of understanding passes between us. Then the friends turn and close the castle gates behind them.

After a ferry crossing to Calais that threatened storms but turned out calm, then a short onward journey by train, Lille station was dimly lit and cavernous.

The crowd clustered round the barrier waiting to board the overnight sleeper to Cannes. Like a guard of honour, the train crew lined up before us. Inside the sixties-built first class sleeper carriage it was dark. With a four person compartment to ouselves, we took a sleeping bag and pillow, a bottle of water, earplugs and other necessities, pulled down the blinds and made ourselves as comfortable as we could. As we lay on our bunks the train seemed to ride the track lightly, bucking and flexing over the steel rails beneath it. The carriages swayed rythmically over the tracks - as if the train was being rocked to sleep by the rails - then suddenly rattled on with a great thundrous clanging. On the doorway and panel above, luminous controls glowed in the half-light. I slept lightly until we arrived in bright sunshine at 10.15 in Cannes, 24 hours after my journey began.

Prematurely sun-aged women in gold shoes and fussy peasant style white dresses, designer shops and gay boys sashaying it to the beach. Determined pleasure-seeking everywhere. After a confusing drive through twisting lanes we found our 'bastide' – once a grand Provençal farmhouse and now the holiday home of one of the City's most successful young investment bankers. Several dusty acres of what was once productive terracing lie behind a high fence and even higher electric gates. A long lavender-lined drive sweeps to improbably lush lawns at the foot of a lovely 3-storey cream building, with a grand balcony off the master bedroom and inside vast cool rough-tiled echoing corridors, a black Murano glass chandelier and a staircase sweeping to our rooms.

A grand Empire style bed and a bathroom with an almost Moorish shower enclosure and a freestanding claw-footed bath. Stunning views over the countryside towards the sea. A deep 'L' shaped pool with the warmest, barely chlorinated water where I swam without a costume in the hot afternoon sunshine.

Tonight we walked for 20 minutes past other impressively protected properties, to the centre of Mougins on the hilltop, where water rushes down a narrow channel from the door of the recently designer re-decorated church. The shops are either galleries, restaurants or estate agents. The well-heeled French are all around us, with the best shod of all at the 'Moulin de Mougins' – one of the best restaurants in France.

Tomorrow perhaps a trip to Grasse, where visitors learn how to blend their own perfume, or more rest and idleness in the shade by the pool. It is strange being in such a marvelously wicked place without a lover.