The scene is straight out of a sci-fi epic or a Bond flick, a vast, mechanised subterranean city buzzing with purposeful activity and operatives in orange boiler suits. This is all that stands between Britain and bedlam. Not bad for a Victorian enterprise a few miles outside Crewe.

It doesn't look like much from the outside. But without Winsford Rock Salt Mine in Cheshire, we would have been in far greater chaos than we were when the big freeze struck this week.
This is Britain's only dedicated salt mine and it is from here that we get most of the rock salt - to give grit its proper name - which keeps the roads open and allows normal life to struggle on against the elements.

As the country slithers around up on the surface, a small team is 500ft underground and working 24 hours a day to feed a queue of lorries collecting the precious commodity of the moment -- sodium chloride.

This is not like any salt mine I ever. imagined. The very term conjures up visions of dissidents and slaves toiling away in some forgotten hell-hole. The Tsars and their Soviet successors, who were fond of sending enemies of the state on indefinite salt mining courses in Siberia, did not do much for the industry's image.

`People always think about Russia when you talk about a salt mine but it's not like that at all,' says Neil Brookes, 46, a third generation salt miner - he would be happy if his own son chose to follow him down this pit. `I've been down coal mines and I wouldn't work there. But this is different.'

It certainly is. For a start, there are just three men doing the actual mining. Yup. A country of 60 million people crying out for grit must rely on a trio of lads from Winsford - plus a monstrous machine that, literally, eats Cheshire for breakfast.

The other thing which strikes me is that the place is so big and so clean (even my guide is called Mr Sheen). Coal mining is a mucky, dangerous industry where seams collapse and gas escapes. The geology of rock salt, though, is very stable. There is no' gas, no mess and the temperature remains at a constant 14 degrees whatever the season. And the whole process is very simple.

You get large chunks of rock salt, put them through a crusher and then stick the residue straight on the road where it prevents snow and ice from settling. And, unlike table salt, this brown stuff needs no refining to satisfy customer tastes.

`See the salt on that conveyor belt,' says Alan Sheen, commercial manager of The De-Icing Business, which owns Winsford. `That could be on a lorry in 40 minutes and sprinkled on a motorway in a couple of hours.'

I wonder why the hell it wasn't on the M40, M42 or M6 on Wednesday night when I spent nine hours crawling through bad-tempered mayhem to get here. But that is not Winsford's fault. They produce a million tons of salt annually and dispatch it all year round to local authorities and the Highways Agency for stockpiling.

Even in the middle of this cold spell, there are 250,000 tons of the stuff ready for collection. Spreading it on the roads is someone else's business.

To reach the bottom of the mine, we have descended in a normal lift so clean that we could be in an office block. We arrive at the bottom of Shaft Number 3. No one is entirely sure why it is here. It was sunk in 1940 by the Government which decided that Winsford was the perfect place to store certain items beyond the reach of every German bomb. To this day, though, no one here knows what the items were.

`People were told that it was mercury and cotton bales, but why would you go to all that trouble just to store cotton?' asks Mr Sheen.

Local legend has it that this was where the Crown Jewels spent the war. They could have stuffed Buckingham Palace, Windsor Castle and Parliament down here, too.

The place is colossal - 22 million cubic metres of void. More than 100 miles of underground road high enough for a double-decker bus connect a labyrinth of vast chambers. In one small section alone, a commercial storage business is thriving, and the entire county archive is down here, too. But even this occupies only a tiny fraction of the emptiness. There is no risk of banging your head at Winsford.

A minibus drives us along the only road in Britain which is never going to need any gritting whatsoever. There is even street lighting and the occasional one-way system.

There are whole buildings down here. `Only one of them is locked,' says Mr Sheen. Which one? `Actually, it's the toilet paper store.'

We drive for miles, passing the occasional team of surveyors or mechanics in their orange suits. I halfwonder when we are about to turn into another huge chamber and find a crazed Blofeld or Dr Strangelove cackling hysterically as he prepares to launch a rocket that will destroy the world.

In one section, we pass a graveyard of redundant diggers and cranes parked in a neat line. `There's no point taking them out, so we leave them down here when we've finished with them,' Mr Sheen explains.

I imagine that everything must corrode pretty quickly, amid all this salt. In fact, because there is no moisture in the air, nothing rusts.

Suddenly, we stumble across a Caterpillar digger the size of a house. It is the biggest tractor I have ever seen - hardly surprising since it is the largest vehicle operating underground anywhere in the world - and it is called Diane.

I wonder which poor Diane inspired that label. It turns out that it is named after the former Blue Peter presenter Diane Louise Jordan, who inaugurated the machine a few years ago. What an honour for a girl.

It costs Ł12,000 every time this thing has a puncture in one of its nine-foot-high wheels. It weighs 80 tons, can scoop up 20 tons of salt in its bucket and gets through 150 gallons of diesel in a shift.

It is so big that The De-Icing Business had to take it to pieces to get it down here and then reassemble it underground. Like all the other machinery, it will never leave.

We drive on, following the miles of conveyor belt, and finally reach the mine face. Through the half-light, the mining machine resembles a stooped dragon peering down on a damsel it is preparing to devour.

A surveyor uses lasers to line it up while the three miners check the dragon's teeth - 86 tungsten spikes which have to be replaced at least once a day.

We all stand back, one of the miners presses his remote control pad and suddenly the dragon is chewing out a brand new cavern amid a cloud of salt.

In just 45 minutes, it makes a tunnel 55ft long and 12ft tall, while the salt is already on its way to the surface.

I had imagined that grit was just grit. These days, it is more like coffee, ground to order for councils who can be as picky as a Starbucks customer wondering whether to have a tall, semi-skimmed latte or a mocha frappuccino.

The most popular product, by far, is Thawrox 6 -- rock salt crushed into six-millimetre granules.

In the early days of gritting, ten millimetre was the norm but it did a lot of damage to windscreens and had a habit of bouncing off the road as it was sprinkled. `We still sell quite a lot of ten millimetre to councils in particularly snowy areas but it's not so efficient on most roads,' says Mr Sheen.

There are optional extra treatments and the grit is then served up to customers in two forms - dry or exposed.

The dry stuff goes off for bagging and will later be shovelled on to pavements to stop us falling over. The exposed stuff, which is destined for the road-gritting machines, is piled into a huge salt mountain outside. A team of diggers shovels it straight into the lorries which will deliver it to councils all over the country.

The cost is the same whatever grit you choose, although no one wants to talk prices. Winsford does not enjoy a monopoly. There is competition in the gritting game. Apparently, a rival company
also produces rock salt from a potash mine in Cleveland. What I do know is that The De-Icing Business has an annual turnover of Ł25 million and produces a million tons every year, so the maths is not too tricky.

They have been producing salt in these parts since Roman times and the Winsford mine has been going since 1844 when a few bold Victorians came down in a bucket. This bit of Cheshire sits on a seam of salt so rich that

Winsford's reserves could last for at least 75 years at the present rate of extraction.
By then, of course, we may have come up with a more efficient way of keeping our roads open whenever a snowflake touches down.

Surely, by the end of the century, Britain will be sufficiently advanced. that it will no longer need to send people down a salt mine just to avoid gridlock.

If this week's shambles is anything to go by, don't bank on it.