'It's brother and sister to me, and aunts, and company, and food and drink and (naturally) washing. It's my world and I don't want any other. What it hasn't got is not worth having, and what it doesn't know is not worth knowing....'

Kenneth Grahame: The Wind in the Willows

THAT was the Water Rat, of course, and he was talking about The River, but there are folk - folk of an age, folk of my age - who wax just as endlessly ecstatic, as deep-end delirious, about steam engines.

One of them was on the special last Saturday, talking on his mobile to some distant-signal friend with all the breathless excitement of Raymond Glendenning essaying a post-war Cup Final commentary on the North Home Service.

"We've come into the north-bound platform at Northallerton, K1 leading, just past that potential curve. I can hardly believe this, I think we're going to shunt..."

There'd been another as the K1 left Darlington for Bishop Auckland, sheep - long since DMUred - turning tail as surely and as sacklessly as on that long gone day in September 1825 when Locomotion No 1 first breathed fire up their backsides.

"My, oh my," he murmured, as the Mole himself had done, and even the locomotive, banshee-wolf whistling and fired with enthusiasm, seemed happy just to be alive on so great and glorious a morning.

There were seven crowded coaches, a great Peter Panoply. There were more cameras than a branch of Dixon's, more flasks than the one o'clock to Windscale. It smelled like a Saturday morning in 1958, and thus it smelled quite wonderful.

This is to be a chronicle of lost childhood.

THE K1 was 62005 and in the days when iron horses were workhorses, too, so ferrously familiar that we raggy-trousered train spotters would hurl imprecations upon its slow lineage.

Now it's one of six steam engines owned, cherished and maintained by the North Eastern Locomotive Preservation Group, and much the hardest working. Many days it can be seen on the North Yorkshire Moors Railway, in summer on the West Highland line.

On Saturday, she - she, now surely - worked a NELPG rail tour around some of the route and branch byways of the North-East's railways.

The volunteer crew had been up since 4.30, the guard 90 minutes earlier to have a pee and throw some coal onto the fire. Most of the passengers had joined about 7am, though it was 9.45 before the column caught up, at Darlington.

Chris Cubitt, the driver, had started his railway career at the age of 15 years and 13 days as an engine cleaner at Thornaby shed and retires next month as a driver on the Trans-Pennine Expresses. He'll still drive on the NYMR.

It was his 28th wedding anniversary. "The difference between this and the wife is that you can leave the K1 in the shed for a month, come back and she'll be as good as gold," he said.

"If I come back home after a few days on the West Highland, there can be hell on."

Someone asked him to take a picture with one of those digital contraptions. He couldn't work it. "I'm an engine driver not a bloody scientist," said Chris.

Peter James, the fireman and a man who calls a spade a shovel, had been brought up in the south-west. For Stockton and Darlington read Somerset and Dorset. They said how much they felt sorry for him. "That's why I'm shovelling coal," said Pete.

It was while we were stopped at Shildon, doing whatever it is that locomotives do at railway stations and from which gentlemen must please refrain, that something utterly orgasmic happened. I was invited to ride through Shildon tunnel, and on to Bishop Auckland, on the footplate.

As bairns we knew that tunnel well, did things in there that certainly we shouldn't have done, waited by its dark portals for the first thrill of an approaching A4 or, querulously, for a Q6.

Those two minutes were amazing, the firelight phantasmagorical, frames and flames fast frozen forever.

Conversely anti-climactic, those camera strap-hanging from every footbridge or in the rapturous reception committee at Bishop railway station may entirely have expected images of a soot-stained engine driver leaning from the cab window, checking if he were on the right road.

Instead there was a jackanapes journalist, crescent-moon faced and Elysian abandoned, heart beating to the rhythm of a long-forgotten age.

LOCH Arkaig, a Type 37 diesel, is at the other end, the journey taking us back through Darlington to Northallerton, up the Wensleydale branch to Leyburn and to Redmire, back to Northallerton, onto the Yarm line to Middlesbrough and thence to seaside, and Saltburn.

About nine-tenths of the passengers are male, about half of the nine-tenths bearded - an aggregate of anoraks some would say, though most appear utterly unzipped.

Inevitably many are getting on a bit, though their passion is by no means spent.

Clergymen are reputed also to be railway buffs, but none of the passengers appears to be in holy orders. A chap bearing a marked resemblance to the present Archbishop of Canterbury turns out to be a council clerk from Crook.

The crew also have a support coach, bunked-up and boisterous, in which Martin Lloyd is on catering duty. A former ICI chemist - he specialised in poisons, the lads say - he's said to do a pretty hot chilli and a Mars Bar trifle that could line the K1's boiler, should the asbestos wall ever take fire.

"There was a trip behind Blue Peter once," someone recalls. "The locomotive failed, but the Mars Bar trifle was brilliant."

There's a raffle, too, the first prize a painting of one of the NELPG locomotives and the eighth and last a lump of K1 coal. Many long for pieces of eighth.

Back in Darlington, diesel hauled but still passion driven, the train waits for 20 minutes on the passing loop next to platform one. It's barely reached Croft before a chap wanders down the carriage asking if it's the first passenger train to leave the platform one loop since the Queen of Scots Pullman in November 1960.

It's difficult to standard gauge the reaction. "Now he," they say - not unkindly - "is what you call an anorak."

IT'S not all beer and vittles, of course. Before first passing Northallerton, they've drunk the buffet dry.

Though the restored Wensleydale Railway is operative from Leeming Bar to Redmire, the section from Northallerton to Leeming is seldom traversed, a clicketty-clack track with the resonance of a John Betjeman poem.

Fields blossom with bluebells and flower with photographers. Bairns at Bedale blow Thomas the Tank Engine whistles in timeless salute. Snappers climb ladders, mothers climb walls.

"You can do this hundreds of times and still the appeal never fades," says Martin Lloyd. "You still want to hang out of the window, still get smuts in your eyes."

Loch Arkaig's still leading, the K1 tagging along behind like a reluctant kid on a trip to an elderly great aunt's, occasional steam escaping, exasperated, from its pistons.

From Redmire railhead the great locomotive - 58-years-old but ageless, utterly - resumes the rundown, whistling while she works. Seven carriages sit back, their occupants eating prodigiously, the train spot on time back into Northallerton. It's been a real steam effort.

FORMED in 1966, the North Eastern Locomotive Preservation Group has around 350 members and depots on the North Yorkshire Moors Railway at Grosmont and in the former Hopetown carriage works in Darlington.

Their literature talks about operating steam engines, not stuffing and mounting them.

Next month they hope to have the Q6, on which in Darlington they've worked for four years, back in steam. About a sixth of the 350 are active workers, skilled and unskilled.

"People tend to think it's just like a giant Hornby-Dublo train set, but there's a bit more to it than that," says Fred Ramshaw - retired Stockton schoolmaster, engine driver and NELPG press officer.

They'd actively welcome enquiries and interest. Details on www.nelpg.org.uk

A footplate ride through Shildon tunnel may take a little longer.