Looking at a map of the British Isles, with its southerly concentration of human settlements, there aren't many places below Cumbria where you might expect to find an extensive landscape that is remote and sparsely populated, especially not one that has remained virtually unchanged since the 1970s.

The coastal region of mid Wales, however, offers exactly that. An area of astonishing beauty, it feels in places as inaccessible as the west Highlands. The most direct route from England is a long A-road, where delays caused by farm vehicles are common, so it is far less visited than one might expect given its proximity to Liverpool and Birmingham, weekenders preferring to pop over the border to the Brecon Beacons or shoot north along dual carriageways to Snowdonia instead.

That means that even at the height of a glorious summer, the roads of mid Wales are delightfully quiet and the pace of life unhurried.

The main towns here are small and laid-back - places like Machynlleth with its New Agey atmosphere and the likeable if slightly battered seaside town of Aberystwyth - but what stands out for the visitor is the landscape. The Ynys-hir RSPB reserve on the estuary of the Dyfi (anglicised as Dovey) has been the setting for BBC's Springwatch for the last three years (though this year it moves to Suffolk). From the visitor centre set on a tree-covered hillside on the south bank of the estuary, the sweeping views over marshland and river mouth give a tremendous sense of space and emptiness. The Victorian coastal railway line from Aberystwyth runs alongside the estuary - right next to which a daring common sandpiper raised her brood on camera two years ago - but there is barely a sign of human occupation to be seen.

The reserve occupies land that was once the estate attached to Queen Victoria's Welsh retreat, Ynyshir Hall. The gracious whitewashed house is now the Ynyshir Hall Hotel, part of the exclusive international Relais & Chateaux group.

The gardens are ravishing. A lush, sweeping lawn drops away from the gravel forecourt in front of the house, edged by mature trees that must have been in their infancy when Queen Victoria and Prince Albert escaped to this outpost with their children. The ground floor has a guest bar, a sumptuous sitting room and a Michelin-starred restaurant along the front of the property with French doors to the garden.

Our accommodation was in the Studio, a single-storey extension to the main house comprising a large bed/sitting room and a bathroom big enough to host a board meeting. The interior design aims to marry innovation and contemporary style with tradition. All the rooms are individually designed and ours had a base tone of grey with contrasting creams and yellows, which was bang on trend, if a little dark. The hotel has no spa, though it is possible to arrange a massage.

We sat down to the tasting menu one evening and found the chef exceptionally accommodating of our dietary foibles. There was a distinctly local flavour to the dishes. Among the 10 beautifully presented plates, highlights included the Perl Wen local cheese, passion fruit sorbet, a delicious miniaturised version of eggs, peas and chips, exquisite turbot and melt-in-the-mouth organic lamb rump.

This hotel has had its share of famous visitors over the years, including, apparently, the Springwatch presenters (the reserve entrance is five minutes' walk away) and it is incredibly peaceful.

A word on prices. A night for two in the Studio, with breakfast, sets you back £550; overall, prices for one night's bed and breakfast at Ynyshir Hall for two people sharing range from £205 to £710. While there are probably a good many people who would spend £205 for a special night in a beautiful hotel, fewer would consider spending £550 or £710 on a night's bed and breakfast, no matter how vast the bed or how artfully arranged the breakfast fruit plate. This is clearly not a hotel for those on a budget; it does however offer luxury, and friendly, unobtrusive service, in a delightful setting.

The key attraction of this corner of Wales is undoubtedly the nature and many guests come to go walking or bird-watching. From Ynyshir Hall, one of the best walks takes you through the Artists Valley, a narrow glen running inland from Eglwys Fach village. A path winds steeply upwards between houses and onto a road edged by ferns and heather. On a warm day in the quiet of the valley, only bumble bees, brightly coloured damselflies and meadow pipits break the silence. The path then dips down below trees into the cool of the valley floor where a burn tumbles over ancient rocks towards the River Dovey. Rising up the other side, the path takes you back onto another deserted road bordered by dense hedgerows of hawthorn and wild honeysuckle. It is possible to do the whole hour-long walk, even in high season, without meeting another soul. Robert Plant of Led Zeppelin perhaps agrees: having co-written Stairway To Heaven with Jimmy Page at a cottage nearby in 1970, the singer now apparently has a house in the area.

Venture north along the A487 towards Machynlleth and you soon come to the Dyfi Osprey Project, which has also featured in Springwatch. While there are well over 200 pairs of ospreys breeding in Scotland each year, Wales has only two pairs, with one of them located here on a man-made platform. The site is run by volunteers who guard the nest in spring and summer 24 hours a day to protect it from egg thieves and prying eyes - if humans, dogs or other perceived threats get too close, the adults fly away from the nest, leaving the eggs or young chicks vulnerable. When we were there, the mother, Glesni, was frightened by the sight of a railway worker and flew off the nest, leaving hatchlings Clarach and Cerist unguarded. Thankfully, she flew back a few minutes later and it wasn't long before her partner Monty was back too, with a large mullet in his beak.

Continuing north past Machynlleth on the A487, there is a site that is so famous it is known by its initials alone: CAT. The Centre for Alternative Technology was set up in the 1960s as an experiment in sustainable living and no visit to this area would be complete without taking a look. It has an education and visitor centre with exhibits and working examples of many types of eco-technology, from photovoltaics to hydropower.

The big thrill is ascending to the main site in a hydraulically powered cable car. With sustainable technologies now increasingly mainstream, the centre does not have the novelty value it once had, but it is possible to while away a pleasant afternoon here, and enjoy an organic lunch in the cafe.

Thirty five miles from Machynlleth in the opposite direction is Harlech, the first of King Edward I's great quartet of formidable north Wales coastal fortresses (the others being Caernarfon, Beaumaris and Conwy). From here, you can continue your Welsh odyssey by moving north into touristy Wales and climbing barren Snowdon, a vigorous walk but easily done in a day. But you may find yourself, as we did, wishing to escape the madding crowds and return to the quiet haven of west Wales.

Travel Notes

Rebecca McQuillan was a guest of Ynyshir Hall Hotel, Eglwysfach, Machynlleth, Powys (ynyshirhall.co.uk, 01654 781209). One night's B&B for two costs from £205; one night's DB&B for two from £350, including six-course dinner.

Getting there

The train to Dovey Junction, 1.5 miles from the hotel, takes seven hours from Glasgow, changing at Wolverhampton. By car it is a 320-mile journey from Glasgow.

What to do

RSPB Ynys-hir (rspb.org.uk/reserves/guide/y/ynys-hir) visitor centre is open daily 9am-5pm, April-October; 10am-4pm, November- March. Non-members: £5 adult, £2.50 child. Dyfi Osprey Project, Glandyfi, Machynlleth (dyfiospreyproject.com, 01654 781414) is open 10am-6pm daily. The Centre for Alternative Technology, Pantperthog, Machynlleth (cat.org.uk, 01654 705950) is open 10am-5pm daily. Adults £8.50, children £4, discounts are available for walkers, cyclists, bus and train travellers.