In every British summer, so I've been told, there's one perfect sunny day. And it seems I've jagged it today, as my narrow-gauge Welsh Highland Railway train trundles through the countryside to Caernarfon.
After we depart Porthmadog, a former slate-mining port on a pretty estuary, its urban backyards are replaced by craggy hills behind meadows with sheep and cattle. With a blue sky above, and the mirror-calm water of lakes along the route, each view seems a postcard cliche of bucolic England.
Though we're not in England, of course, but north Wales, a bastion of Celtic culture. In hotels, shops and pubs in Porthmadog, it's common to hear Welsh words being bandied about by locals of all ages.
The local Celtic tongue is not the only great survivor in these parts. Though it's home to a mere 4000 people, Porthmadog has three railway stations, serving mainline trains and three narrow-gauge heritage railways. This town is a rail enthusiast's dream come true.
WELSH HIGHLAND RAILWAY
The 40-kilometre-long Welsh Highland Railway was knitted together in 1921 from separate narrow-gauge railways serving slate quarries. Sadly, it was a near-instant failure. Faced with competition from modern buses, its dated,slow trains were unpopular with passengers and the line closed the following decade.
That era's loss was our gain, however. The railway's scenic route proved perfect for tourists, so it eventually reopened in 2011. Passing through Snowdonia National Park and the beautiful Aberglaslyn Pass, and finishing near one of Wales' most impressive castles, on a good day this train trip is a visual treat.
And this is a good day. Pulled by the world's most powerful narrow-gauge steam engines, we twist and turn up the slopes after the village of Beddgelert, gaining height through tight cuttings lined with green moss.
After we pass the highest point of the line, the countryside opens up and we gaze upon Lake Cwellyn, framed between the grassy slopes of a valley.
In the other direction is a contrasting view – mighty waste tips of slate, discarded in the mining days as only a portion of the excavated slate was usable. Though a jarring contrast it also has a certain gritty appeal, and is a good reminder of how this railway began.
First class, where I'm seated, has just two seats across the narrow carriage – one each side of the aisle – and they're comfortable armchairs with blue carpet underfoot. Shelling out the extra for first class seems a good option, as there is more space and it's easy to move around and take photos.
The catering on board is surprisingly plentiful, given the two-hour journey: hot dishes include "Welsh beef madras", baked steak and ale pudding, and a three-cheese pasta and broccoli bake. There's also Welsh afternoon tea on the way back, with two scone-like welsh cakes and a slice of bara brith (fruit bread).
At the end of the ride there's enough time to walk around Caernarfon before the return leg. Caernarfon Castle is the undoubted highlight here, looking like the Hollywood ideal of a castle with intimidating stone battlements.
The medieval fortification is from the 13th century, the railway from the 20th – yet somehow they go together perfectly, like bara brith and butter.
The second narrow-gauge railway which runs from Porthmadog is the Ffestiniog Railway, whose trains depart from the same station as the Welsh Highland Railway. This is the oldest surviving railway company in the world (and now also operates the WHR).
Founded in 1832 and originally using horses to haul its carriages, its steam-driven passenger services began in 1865.
After World War II the FR's slate operations ceased, but decades of work gradually transformed the mountain-hugging route into a tourist railway. In 1982 the line reopened for the 75-minute haul to the former slate-mining town of Blaenau Ffestiniog, and since then it's become one of the most popular attractions in north Wales.
Having boarded, I can see why. It may not be as sunny today as on our jaunt to Caernarfon, but almost immediately we're borne into the hilly terrain of Snowdonia National Park.
There are narrow cuttings to traverse as the train heads upward along its 22-kilometre journey. This is a notably more rugged route than that of the Welsh Highland Railway, with rocky slopes and wilder vegetation. Pausing at Tan y Bwlch, the train takes on water, as if gathering strength for the rest of the climb.
At Ddualt we ascend a spiral section of track, constructed in the 1960s to avoid a nearby hydro-electric power station. Passing the power station's dam at Tanygrisiau, we perch above tall grey houses with slate roofs as we approach stony slopes hung with low cloud.
Near the end of the trip we observe vast slate tips, then we're gently deposited at Blaenau Ffestiniog. The Ffestiniog Railway station is right next to the town's mainline terminus, so it's possible to use the FR as a bridge between standard train services to the north and south.
A slate-grey town surrounded by mountains, including the imposing Moelwyn Mawr, Blaenau has enough shops and cafes for an hour or two's amusement.
One of the more atmospheric places to visit is Cell B, a former police station which has been transformed into a community hangout including a cinema, cafe and youth hostel. The cafe is pleasant on a drizzly day, with a pot-belly stove warming up its interior.
On the streets, I'm fascinated by the strips of slate set into the town's footpaths, each bearing a popular Welsh expression.
My favourite, I decide, is "Yma o hyd!" Meaning "Still here!", it's a reminder of survival – of the town, its language, and the railway itself.
WELSH HIGHLAND HERITAGE RAILWAY
Not to be confused with the Welsh Highland Railway, this volunteer-run operation is based at the third train station in Porthmadog, next to the mainline passenger station north of the town.
It runs brief narrow-gauge train trips to Pen-y-Mount Junction, along a 1.6-kilometre section of track which was part of the original Welsh Highland Railway. On the return journey the train calls at Gelert's Farm, where passengers can enjoy a miniature railway ride and browse museum displays.
When I arrive for the last departure of the day, the weather has turned so wet and miserable that I'm the only passenger.
I rather enjoy my short private trip within a splendid timber carriage, and there's a lot to look at in the museum. If you want to learn about the history of the region's narrow-gauge railways, this is the place to come.
The prize exhibit here is Russell, a steam engine built in 1906 for the original WHR and now beautifully restored. In gleaming red paint, surmounted by a black funnel, it looks like a character from Thomas the Tank Engine. As a rail fan, I couldn't be more delighted.
Yr Hen Fecws, henfecws.com. Simple but comfortable B&B in the centre of Porthmadog, an easy walk to the WHR and Ffestiniog Railway stations. From £70 a night.
Portmeirion, portmeirion-village.com. This Italianate village was featured in the 1967 cult TV series, The Prisoner. It's a beautiful place to stay, either at the waterside hotel or in one of the rooms scattered through the site. The hotel's shuttle bus can drop you at the Ffestiniog Railway station in nearby Minffordd. From £105 a night.
The Welsh Highland Railway operates from Porthmadog Harbour Station. Porthmadog-Caernarfon fares from £26.70 in third class, book via festrail.co.uk
The Ffestiniog Railway also runs from from Porthmadog Harbour Station. Porthmadog-Blaenau Ffestiniog fares from £16.10 in third class, book at festrail.co.uk
The Welsh Highland Heritage Railway operates from April to October, one-way fare £4.50. See whr.co.uk
Tim Richards travelled courtesy of Cathay Pacific and Visit Britain.
LITTLE RAILWAYS OF WALES
Wales is dotted with narrow-gauge heritage railways, a legacy of its industrial past. Here are six more to try.
1 BALA LAKE RAILWAY
Runs along the southern shore of Bala Lake in north Wales, hauled by historic slate quarry locomotives. See bala-lake-railway.co.uk
2 BRECON MOUNTAIN RAILWAY
Runs rail excursions into Brecon Beacons National Park. See bmr.wales
3 SNOWDON MOUNTAIN RAILWAY
Travels from Llanberis to the summit of Mount Snowdon, the highest peak in Wales. See www.snowdonrailway.co.uk
4 TALYLLYN RAILWAY
Operates from coastal Tywyn through the attractive Fathew Valley to Nant Gwernol near the village of Abergynolwyn. See www.talyllyn.co.uk
5 VALE OF RHEIDOL RAILWAY
Takes in impressive scenery along its 19-kilometre route between coastal Aberystwyth and Devil's Bridge. See www.rheidolrailway.co.uk
6 WELSHPOOL & LLANFAIR LIGHT RAILWAY
Runs from a station near Powis Castle outside Welshpool, to Llanfair Caereinion. See www.wllr.org.uk