The Witch's Pool charmed Hero Brown, but her plan to see the Brecon Beacons by bike was jinxed
"IF YOU go in the middle of winter, what do you expect?" said my friend when I phoned to tell her my first day in the Brecon Beacons had been rained off. She was right. Even in summer, the weather in this part of South Wales is hugely changeable, and conditions can become dangerous on the higher peaks (which is, no doubt, why the SAS trains here). But, stuffed full of Christmas food, it seemed like a good idea - no, it was a good idea. Even with the black skies and my boyfriend confined to bed (albeit a comfortable four-poster) by flu for our three-day stay, I still enjoyed myself.

The least well-known of Wales's three National Parks - Snowdonia and Pembrokeshire Coast are the others - the Brecon Beacons has been dogged by tourist board in-fighting, which has undermined its strengths as a hiking and mountain biking hot spot. I had come to check out the biking myself, as well as to do some walking around the 520-sq-mile park in a three-day "blitz".

Biking, unfortunately, was off. My guide, Keith Lee, from local specialist Hikes and Bikes, advised against it (weather again), although he confirmed what I had already been told - that these hills offer the best biking in the country. Instead, I discovered the Beacons on foot.

I was staying in the small village of Crickhowell, about 18 miles from Brecon. It was hard to believe it had taken only one hour to reach the village from Cardiff (itself only two hours from London by train), so magically remote did it feel. Crickhowell managed a friendly welcome even under the clouds, with its effusive, largely Welsh-speaking locals, half a dozen or so quaint pubs scattered around its tiny centre and a clutch of quality hotels and b&bs.

On my first day, I watched cold canoers struggle against the muscle of the River Usk which flows muddily beneath a lovely 17th-century bridge at the bottom of the village. (In season, I was told, the river provides locals with good salmon and, further up, trout fishing.) Ramblers strolled along the walkway, while a couple of frustrated young bikers stuck to the low land, practising their bike tricks. I spent a pleasant, if somewhat soggy, afternoon following the river, shadowed by the flat-topped Table Mountain which, like a protective brother, dramatically hovers behind the village.

The next day I resolved to explore. The scenic drive from Crickhowell to Brecon was the perfect mood-setter, the sky a bright smudge of blue and white, the upper mountains peppered with the previous night's snow. Keith met me in Brecon and together we drove five miles to the village of Talybont, which was to be our starting point.

I had earlier told Keith I'd like to do a four-hour hike, but while I was hoping to climb the two highest peaks, Pen-y-Fan (2,907ft, and the venue for the SAS iron man competition: record, 39 minutes to the top with full pack. Don't try it) and Cwm-du (2,863ft), weather dictated a new course. Keith decided to take me on a little-used route, unknown to most tourists.

A gradual ascent up Tor-y-Foel (1,800ft) in the Black Mountains on a 19th-century tram road took us through heavy woodland. "Mud" is the word that springs to mind. But when I wasn't concentrating on my footing and instead looked at the views, I felt a surge of appreciation for the Beacons. The area is a canvas of waterfalls, creeks and wild contours. Even in deepest winter, the countryside offered a myriad of bronzes, purples, greens and reds.

We started the final, steep climb to the top of Tor-y-Foel, above the cloud cover, and snow suddenly began. By the time we reached the top of the mountain, visibility was poor, I was freezing, and Keith had to describe the wonderful views. But there was some light relief when he pointed out grouse, red kites and circling buzzards.

An hour's slide downhill took us to road level at the village of Llangynidr. There we started a pretty, protected walk along a canal, where we saw the electric-blue of a feeding Kingfisher. By the time we returned to my car, hours later, the sun was shining again and I wore my muddy clothes like medals. I felt I'd achieved something.

My last day was wet again so Keith drove me to a Bronze-Age burial ground and an unmarked Stonehenge-like stone circle, which is ignored by most tourists who seem to think the boulders are a modern signal of where to park their cars. We saw two ruined castles (Raglan and Castel Gwyn on the English border) and the eerily beautiful Llanthony Priory. We even took a magical late-afternoon stroll around the Pwll-y-Wrach waterfall (wonderfully translated as "Witch's Pool") in Talgarth before I headed for home, the spell broken.

Hero Brown was a guest of The Bear Hotel, Crickhowell (tel: 01873 810 408). Her guide was Keith Lee, from local outdoor specialists Hikes and Bikes, 10 The Street, Brecon (tel: 01874 610 071). Wales Tourist Board (tel: 01222 499909) or the Brecon Beacons National Park Centre (tel: 01874 623156).