Bristol Channel: My (almost) private island paradise

Is the Bristol Channel one of our most exclusive holiday spots? Simon Heptinstall thinks so

Lying on my soft grassy rock I could just make out the packed beaches of Barry Island and Penarth in South Wales. And if I rolled over the other way I could see the crowded resorts of North Somerset and Devon.

I was sitting by myself, listening to waves gently lapping against the shore. I'd discovered an unspoilt oasis right in the middle of one of Britain's most popular seaside areas. This was my reward for finding how to get on to the get-away-from-it-all islands of Flatholm and Steepholm in the middle of the Bristol Channel.

Thousands gaze from those busy coasts wondering how to reach the two mysterious islands standing a few miles offshore. Boat trips are rarely advertised; visitor numbers are limited and no one can just turn up and hop aboard.

Despite their enviable location on our coast, Flatholm and Steepholm are not holiday islands. They are designated Sites of Special Scientific Interest and Nature Reserves. One is owned by a council, one by a charitable conservation trust and all development is strictly controlled.

It is, in fact, easy to take a trip to either island, but not both in the same day. The Holms are only three miles apart but the Flatholm boat leaves from Barry in South Wales while the Steepholm boat goes from Weston-super-Mare, 100 miles away by road.

That's partly because the main shipping channel runs between the two islands. Also, Flatholm is considered part of Wales, while Steepholm is administered from England.

The key to getting out there lies in two phone numbers. For Flatholm call 01446 747661; for Steepholm ring 01934 632307. There are regular day-return boats, although extreme tidal ranges and unruly waters mean trips are often cancelled. I waited weeks for my trip to Steepholm to get the go-ahead. Flatholm's service is more reliable; Steepholm is more expensive but more memorable.

Once you get on either of the boats you realise a real adventure is beginning. Vital supplies are loaded on board to be ferried to the island's resident wardens, and detailed safety instructions have to be given to all passengers. For safety reasons children under five are not allowed.

It takes an hour to cross from Weston to Steepholm, 40 minutes from Barry to Flatholm. The Channel that looks so calm from the shore gets pretty choppy. The tidal flow out there is one of the world's most extreme, rising and falling by 47 feet. Currents are stronger than any swimmer, so neither island allows any bathing.

Indeed, some trips get all the way to the islands only to find it is too rough to land. And visitors have often been stranded. Flatholm warden Natalie Taylor was stranded on the island when she went for her job interview. "I had to stay for an extra day – it was no problem," she shrugs with a nonchalance that probably guaranteed her success in landing the job.

The trip to Steepholm is usually taken in the 100-seater Bristol Queen. Landing involves simply charging the boat full pelt into the steep beach, then walking along a wobbling gangplank to shore.

Stumbling up that pebble slope I suddenly felt stupidly intrepid. I stood on the beach for a while savouring the moment as the treacherous waters swirled around the shore and the cliffs towered above.

Steepholm is a mile-long sausage shape with 250ft cliffs all round and a wildly overgrown plateau on top. Visitors are free to clamber up the path and wander around the 50 acres. Because of the tides, most trips leave you on the island for eight to 10 hours.

Surprisingly I never got bored. I did a complete circuit, investigated ruined Victorian fortifications, stared at the views, sunbathed, beachcombed and watched seagulls. There's a wind-powered café and shop in an old barrack building. You can buy Steepholm stamps, history books or cakes. I sat outside there for a while but other people seemed to spoil the effect and I soon headed off for the solitude of rocks.

The café, the boat and, indeed, the whole island are run by members of the Kenneth Allsop Trust. They are nature lovers who bought Steepholm 28 years ago as a memorial to the popular TV naturalist. Their president is Lyme Regis-based author John Fowles.

A few weeks later I went to Flatholm to make a comparison. As the name implies, this is a low-rise medallion of rock about half a mile across. Cardiff Council owns the island and its boat, the Lewis Alexandria. They plan sailings throughout the year, almost daily in summer. There's a limit of 50 people on the island at any one time and guests sleep in bunk-bedded rooms in a farmhouse and converted barracks.

With its own jetty, it's easier to land on Flatholm. Once ashore the paths are clearer and facilities better maintained. But day trippers are allowed only three hours, which is mostly taken up with being given a guided tour of the lighthouse, gun emplacements and rare plants. You can't roam by yourself.

So are these two limestone humps worth a visit? The boat trip, views and feeling of adventure make for an interesting day, but you can't help thinking the islands are sadly underused. Only 3,000 people get to visit each year.

I couldn't suppress the feeling that the Holms are never going to be as fantastic as they could be if I were a billionaire and owned them. But then they've got a bit of a track record of being slightly useless. During the Second World War there were hundreds of men stationed on the islands. They fired millions of rounds of anti-aircraft fire at German bombers heading for Cardiff and Bristol, evidently failing to shoot down a single one.