‘I need not tell you that whilst the Sun gilds our Hemisphere this situation is most delightfull,’ wrote Lady Bulkeley of Baron Hill, Anglesey, in about 1760. Having arrived on a January afternoon, beneath a sky that turned lurid shades of turquoise and tangerine, I beg to confirm her opinion. ‘I have now under my Window,’ she continued, ‘seven very large Vessels which is no small addition to this pretty prospect.’ Boats still furnish the view, not least during the Royal Anglesey Yacht Club’s regatta week; among those raced is the Menai Strait One Design, a 20ft mahogany and oak classic, whose design dates from 1937, to be found here and nowhere else.

And this is the key to Ynys Môn. The largest Welsh island, 278 sq miles in total, has places of rare beauty. A northern shoulder of the island that must have reminded somebody of the Highlands (it’s known locally as Little Scotland) has hidden rocky coves and sandy beaches to be reached by car or enjoyed as views from pubs. However, Anglesey’s secrets are best unlocked by boat. Dark lanes smelling of leaf mould are replaced by a bright sheet of deceptively tranquil water, crossing which can be exceptionally bracing, and, like other island channels, has led many mariners to their doom.

Frost had bleached the colour from the fields, ice sparkled on the stone steps of my apartment and my hand nearly froze to the iron rail. Just the morning, then, to go out on the Menai Strait on a rib. Phil Scott of RibRide (www.ribride.co.uk), who took me, didn’t seem to mind turning out in the cold. Having grown up in Newcastle, he came to Anglesey for the water sports 20 years ago, and the joy of the place hasn’t palled.

‘I’ve been getting more business since the announcement of the wedding and even had Ben Fogle out with me last week.’ The island is so popular that Mr Scott hadn’t been able to get a reservation at his favourite restaurant-The Bull, at Beaumaris-on the previous Saturday night. Instead, he and his wife ate at Neuadd Lwyd, original seat of the Tudors, where Prince Charles stayed when he visited William.

We launched from a jetty at Moel-y-Don (Crest of the Wave); in 1282, a bridge of linked boats was built here under the orders of Edward I, but when his captain Luc de Tany led a force across it to attack the Welsh in Snowdonia, he himself was attacked, forced back in confusion, and he and his men drowned in the fast-moving tide.

Curlews were calling as we went out; the water was as still as glass. Nothing stirred at Pilot’s Cove, where the white cottages once occupied by the pilots who guided vessels through the Strait are now holiday lets. There was nobody on the dunes at Newborough Warren, or the isthmus of Llanddwyn Island. It’s a place to admire the basaltic pillow lava, one of the many rock formations in what is now a European GeoPark.

Fort Belan, across the Menai Strait, begun by Thomas Wynn as a private act of patriotism during the American Revolution, when privateers were a menace to shipping, could have been etched onto the scene, for all the movement it showed. You wouldn’t expect many people to be about during winter, but such places must feel as remote as anywhere in the UK, even in summer; not many make it to the end of the Dinlle Peninsula, where the fort stands. If even a prince and his princess want to be alone on Anglesey, they can be.

The locals, like most friends of the Royal Family, are fiercely protective of their own. Gwen McCreadie of Anglesey Farms (www.angleseyfarms.com) is born and bred on the island ‘and wouldn’t live anywhere else’. She and her husband run an award-winning B&B, Deri Isaf, and the Derimôn smokery, for which Mr McCreadie catches the eels. ‘We’re proud of ourselves that we’ve been able to give them [William and Catherine] the peace and privacy to enjoy life. But it’s very exciting and, at the end of the day, we’re all romantics at heart,’ says Mrs McCreadie, who acknowledges that the arrival of the royal couple has ‘certainly put Anglesey on the world map’.

Nothing could augur better for Prince William and his bride’s happiness than Anglesey’s affection for them. It may not possess the grand mountain scenery of other parts of the principality (what is ambitiously called Holyhead Mountain rises to a mere 722ft), but when clouds set in over Snowdon, on the mainland, Ynys Môn may still be bathed in sunshine.

This is precisely why the search-and-rescue station at RAF Valley where the Prince works was established there in 1941. It soon acquired the motto In Adversis Perfugium (‘A Refuge in Adversity’), which now seems an apt motto for the island. Squadron Leader ‘Spike’ Wright, CO of C Flight, 22 squadron (William’s flight commander at RAF Valley), is firm in his view of Flt-Lt Wales: ‘He is dedicated, capable, keen to succeed and enjoys working beside us just as we enjoy working beside him. He loves the flying and the good we do in our job.’

Known as Mam Cymru, the Mother of Wales, the island’s interior is a patchwork of small fields, villages and market towns, with a smat-tering of new houses built after the opening of Wylfa nuclear power station in 1971. You would have to be a connoisseur to know that Admiral Lord Clarence Edward Paget, younger son of the 1st Marquess of Anglesey of Plas Newydd (now owned by the National Trust), sculpted a statue of Nelson that looks out from the shore beside the north pier of Britannia Bridge, towards the perilous whirlpools of the Swellies. ‘If you can sail the Menai Strait,’ said England’s most famous naval hero, ‘you can sail anywhere in the world.’

The Marquess, nearly in his nineties, speaks with great affection of growing up on the island and bringing back his young bride to Plas Newydd. He found himself ‘alone in the large house with tremendous bills mounting up’. His advisors suggested he sell, but he wasn’t giving up without a fight and contacted the National Trust. ‘To my huge relief, it took on Plas Newydd and we continue to live in the house, opening the great rooms to the public.’

He and Lady Anglesey weren’t quite facing the challenges that lie ahead for William and Catherine, but there were challenges nonetheless. Perhaps the greatest draw, apart from the view, is the great mural by Rex Whistler, acknowledged to be his biggest and most interesting work. Lord Anglesey admitted that if he had to choose a favourite place on the island, it would be the view from
Plas Newydd: ‘After all, this is my life.’

The fact that the first Land Rover was created on the island by a farmer, Maurice Wilks, who happened to be chief designer for Rover cars, should come as no surprise. In 1946, Mr Wilks had been wanting a replacement for his old ex-forces Jeep, but found that none was available. He used materials that were readily available after the Second World War, such as Birmabright aluminum alloy and the light green paint used for aeroplane cockpits.

Anglesey remains Land Rover country: an out-of-doors place where there are still red squirrels; the woods and hedgerows contain some of the finest wild-bird shooting, particularly woodcock, to be found in Britain; and in the fields, there are hardy, Welsh black cattle and rugged mountain sheep (so do-it-themselves that they’d run from a farmer at lambing time). Anglesey folk have a rare number of butchers to choose from-and choose they do, with connoisseurship that most reserve for wine.

Like other islands, it hasn’t hurried to catch up with the 21st century. ‘That little church is still lit by candles,’ somebody told me. ‘If you go for a wedding, you have to be careful your hat doesn’t catch fire.’

William and Catherine are not the first to discover Anglesey, of course. It was so well populated in prehistoric times that every other field seems to contain a burial chamber, and the stumps of limestone walls survive from an Iron Age settlement at Din Lligwy. Valuable because of its copper mines, Anglesey was a fastness of the mysterious Druids back then.

The Roman general Paulinus met a weird sight when he landed to conquer the island in ad61: priests, standing next to fires of human sacrifice, implored divine protection, as painted, shrieking nude women ran with lighted torches among the warriors. His men soon recovered their composure and slaughtered all whom they could reach, but Boedicea’s revolt in East Anglia forced this invasion to retreat.

In ad78, Agricola attacked, in revenge for the near annihilation of a cavalry squadron. Without boats, he had a band of auxiliaries swim the Strait, presumably taking advantage of low tide (it’s possible to walk across if you know the sands). In the face of such prowess, the native tribe collapsed.

In 1294, another ruler, Edward I, was impelled to subdue the island, after Madog ap Llywelyn led a revolt, during which the Sheriff of Anglesey, Sir Roger de Puleston, was hanged. Beaumaris Castle (never fully finished) was the result.

Don’t look for 18th-century splendour, however: Henry Skrine, who visited in the 1790s, found ‘the rugged and ill cultivated aspect’ that bespoke poverty, with dirt roads that became bogs in bad weather. But the copper mines at Parys Mountain built the port of Amlwch, and the Act of Union with Ireland (1800) raised hopes of a booming port at Holyhead. To link London with Holyhead, Thomas Telford built a road, roughly what is now the A5, that began at one arch (Marble Arch) and ended at another (Admiralty Arch at Holyhead). His Menai Suspension Bridge, a world first, arrived in 1826, despite the opposition of ferry owners. But Holyhead remained something of a disappointment, until the railway-carried by another bridge, the Britannia, this time by Robert Stephen-son-came puffing up in 1850.

And so back to the boat and past the Caernarvon Castle on our right-hand side. Past Plas Newydd, which still preserves the trouser leg cut from the 1st Marquess after his knee was shattered by grapeshot at the Battle of Waterloo, and onto the Britannia Bridge. Looking up, you see that it’s guarded by lions, the prototypes for those around the base of Nelson’s column in Trafalgar Square.

What an appropriate symbol for what has become a royal island. When William and Catherine arrive there after their honeymoon, it will be springtime. John Betjeman knew the ‘multiple lark-song, whispering bents, the thymy, turfy and salty scents’ of a countryside bursting into life with famous rhododendrons and a host of wildflowers. We wish them well: they have the world and, most especially, Anglesey behind them.

Clive stayed at The Outbuildings (01248 430132 www.theoutbuildings.co.uk)