A private island for £10 a night? Just don't expect a helipad - or even electricity. Natasha Edwards enjoys her own slice of eco-heaven off Brittany's coast

As we collected our keys at the Office de Tourisme, we signed a charter promising to respect the environment, to limit our use of electricity - the gîtes are powered by solar panels - to conserve water and not to pick the wild flowers. They also gave us the vital sheet listing the times each day when the tide is low enough for the island to be accessible by foot.

From the port, we wound ou way along the Sentier des Douaniers coastal path, then scrambled down the pink rocks from the wooded headland known as the Castel. Although we had been told that it was only a 10-minute walk, it wasn't that easy carrying luggage and provisions. Pots, pans and blankets are supplied, but you have to take your own food, wine and sheets so clever packing and sensible shoes are recommended.

A tiny, lozenge-shaped, uninhabited lump of granite sticking up in the Baie de Lannion, 1km long and barely 300m wide, Milliau is the largest of the scattered Iles du Trégor. What it boasts is total calm, just minutes from the family-oriented resort of Trébeurden. It has beautiful sea views, a fascinating panorama of little rocks and islets, and an exceptional array of wildlife - 275 species of plant have been recorded here. They provide a feast of colour in combination with the rock "chaos": eruptions of pink granite eroded underground over the centuries have been further sculpted by wind, rain and sea into boulders that resemble strange heads and noses.

On its more sheltered north-east slope, the island is lushly wooded with cypress, oak and chestnut trees. These give way higher up to a moorland of bracken and gorse, hedges of honey-suckle and sloe, and vibrant swathes of purple heather. As to fauna, we saw gulls, skylarks, butterflies, large ravens and the odd bird of prey. Apparently there are seals, though you have to be lucky to spot them. Later in the season sheep graze the land. Above all, the island is populated by rabbits, far too many to count. They leapt out as we walked along the footpaths and gathered in ever-growing numbers in the cropped fields that surround the old farm buildings where we were to stay.

Milliau may be uninhabited today, but with a history of human settlement going back thousands of years, the island is like a microcosm of the Brittany coast, minus the campsites and villas but with the rugged beauty and that uniquely Celtic mix of religion, superstition, magic and ancient myth. A neolithic covered alley - two rows of stones, with three long slabs on top - that dates back thousands of years is one of the most impressive of the ancient dolmens, menhirs and alleyways that pepper the region. Nearby, at the back of our cottage, a small vaulted room is possibly the remains of the hermit cell of the monk Meilaw (hence Milliau), who arrived here in the sixth century from Wales or Ireland to evangelise the area.

By the Middle Ages, farmers had settled the island, becoming tenants of the powerful Cistercian abbey of Bégard. In the 16th century, they built an L-shaped farmhouse out of big blocks of the pinky-orange stone, and it now contains the gîte. Today, the island belongs to the Conservatoire du Littoral, the state-owned coastal trust, which manages the land and restores footpaths.

Perched on the highest point of the island, there's also a grand residence harking back to the brief period in the 1920s when le tout Paris would descend here. They were paying court to the 1926 Nobel peace prize winner, the politician Aristide Briand, whose mistress Lucie Jourdan had been given the island by a former lover. Abandoned after Briand's death in 1932, today the doors are bricked up, walls daubed with graffiti and, sadly, although the terrace offers unbroken views out to sea, the house will probably be demolished.

Accommodation in the gîte is rudimentary though picturesque. Downstairs, there's a single room with exposed stone walls, a massive fireplace, an antique Breton armoire, long dining-table, fridge and gas cooker. Upstairs there's a bright, white attic dormitory. Toilets, shower and cold running water for washing-up are in a small hut the other side of the farmyard.

"What, there's no shop!" exclaimed Jean-Pierre, who sees himself as an urban sophisticate, with a typically Parisian inability to live without constant access to a café, a tabac and a pharmacy. True, there was a near crisis when the corkscrew broke, ensuring delicate operations with a sharp knife and potato peeler to dig out the cork.

Once you've done the circular path that hugs the cliff and climbed up to Briand's house, that's about it. But that's the point: total calm and the luxury of absolutely nothing to do except count the rabbits and watch the odd gull flying overhead. While Jean-Pierre retired to read Le Monde, my daughter Olivia and I explored the rock pools by the jetty in La Baie des Pirates, and the dramatic rock formations overhanging the sea in the Vallée des Fées where, apparently, the choir of the Paris opera once gave a concert for Aristide Briand.

At high tide, we were truly cut off, marooned, just as monk Meilaw had been all those years ago. At dusk, the mainland was illuminated by the occasional car headlight passing along the coast.

Too much seclusion? The Office de Tourisme limits stays to two or three days, though whether this is to stop urbanites from going crazy or to prevent you from truly adopting the island as your own, it doesn't let on. We certainly felt quite proprietorial towards this small patch of land by the end of our stay.

The next morning, when the warden for the Conservatoire du Littoral arrived to open the small exhibition in one of the buildings, and the diving school moored off the jetty, it felt rather like an invasion of our territory.

With the midday low tide approaching, we packed our bags and made our way back along the path to where the sandy isthmus was emerging. As we made for the mainland under a distinctly Breton drizzle, new arrivals to "our" island were scrambling down the rocks on the other side.


Getting There

Trébeurden is at the western end of the Côte de Granit Rose, part of the Côtes d'Armor, in Brittany. Brittany Ferries (08703 665333; www.brittany-ferries.com) runs regular services between Plymouth and Roscoff (70km west of Trébeurden), and Portsmouth and St-Malo (167km east of Trébeurden). Ryanair (0906 270 5656; www.ryanair.com) serves Dinard airport (154km from Trébeurden) from Luton and Stansted. TGV trains (www.sncf.fr) from Paris arrive at Lannion, 10km away.

Staying There

The gîtes on Ile Milliau can be reserved at the Office de Tourisme at Trébeurden (00 33 2 96 23 51 64; www.trebeurden.fr) from April to September for €15 (£10.70) per person per night. Gîtes sleeping three to five people cost €60 (£43) per night; €90 (£64) for five to seven people; and €120 (£86) for seven to nine people. For those not staying the night, the Ile Milliau is accessible for between one and-a-quarter and three-and-a-half hours some 20 days per month. Ask at the tourist office for times and tides.