Notebook: Fatal mix of thick fog and nonchalance: Visibility poor. But few drivers heed police warnings to stay at home as the traditional season of motorway pile-ups gets underway

TWO DAYS after seven people perished and scores were injured in foggy pile-ups in the north of England and Midlands, I accompanied Sergeant Tony de Vos of the Nottingham Constabulary's traffic police on his M1 shift.

Fog was patchy, though dense; on some stretches, white, brittle fields were just visible through an icy haze. Traffic was heavy, smearing the livery of his three-litre Vauxhall Senator with salt, grease and mud. An Alfa-Romeo passed in the fast lane. Sergeant de Vos hit a button on his hi-tech display panel. An illuminated clock began measuring the distance we were travelling. 'We'll lock on to him and see what happens,' he said. He allowed the Alfa-Romeo to forge ahead, then moved into the fast lane. 'This guy's taking his speed up now. He's leaving us.' Cars between us and the Alfa, barely visible in the swirling distance, pulled into the centre lane to let the police vehicle through. 'He's leaving us. I'm doing 90 and he's well in front.'

The Alfa driver must have spotted us in his mirror, for he too pulled over. The sergeant eased his foot off the accelerator and drew level, staying with the Alfa for a few moments at 70mph. Its driver, a young man, pretended to ignore us, his elbow on the car's window ledge and his face relaxed. 'He's feigning nonchalance - they all do,' Sergeant de Vos said. 'But we've done our job. He's thinking now.'

Sergeant de Vos and 12 traffic constables are responsible for an 11-mile stretch of motorway. Monday's calamity was in Derbyshire, north of his territory. Three died when a lorry jack- knifed on the southbound carriageway near Ripley, triggering a series of smaller incidents. Elsewhere, vehicles slammed into one another despite fog warnings, holding up traffic for hours. 'At peak periods, when all three lanes close down, traffic builds up a mile every three minutes,' the officer said.

That's what happened on Monday, costing motorway service areas a small fortune in lost business. Sergeant de Vos's headquarters are a low, flat- roofed building in the Granada service area at Trowell, between junctions 25 and 26 just south of Nottingham. He and his men eat their lunchtime sandwiches at the area's restaurant. 'Monday's pile-up left the restaurant empty,' he said. 'When the road was finally cleared, motorists flooded in for tea and the toilet. In the few hours afterwards, the restaurant did pounds 4,000 of business.'

Sergeant de Vos is direct of speech and quietly affable, seems dedicated to his job and, despite the number of road freaks, believes motorways are 'still a very safe method of transport'. Born locally in Newark, he was promoted to sergeant nine years ago, and has been on this stretch of motorway for the past six. In that period, traffic volume on his 17 miles has risen from 42,000 to 94,000 vehicles a day. On an average shift, he travels 150 miles up and down the M1.

IN THE boot of the Senator are 12 road cones, three accident warning signs, a first-aid kit, a shovel and brush, a fire-extinguisher, a crowbar ('that's the most important; a crowbar is going to save a life more often than anything else'), and a 'body blanket' of light tarpaulin. There is also a steel box, bolted to the floor, and accessible by pulling down the rear seat's back-rest. Last week it was empty, but occasionally it contains firearms. Behind the driver's seat, Sergeant de Vos has a large flashlamp fashioned from a section of plastic drainpipe and the door-handle of a Ford Cortina, its beam so strong it can blind; and a small attache case containing his 'staff', a 12-inch baton. A further weapon is the Senator's 24- valve engine, capable of 150mph.

He locked on to a small Renault that spurted through thin fog, hogging the fast lane. The clock monitor span as we gave chase. The Renault nipped into the centre lane and slowed. The fog thickened. Sergeant de Vos pulled into the nearside lane again. I glanced in my rear-view mirror (patrol cars have two of them). Dark shapes of lorries loomed behind us. 'A pea- souper,' my driver observed.

It had a claustrophic density, more frightening than the notorious pea- soupers of yesteryear. Only luck seemed a protection within this M1 shroud. London's Victorian fogs were worse, I imagine, but they lacked the ominous growl of giant trucks and the machismo of modern drivers. For Charles Dickens and Wilkie Collins they were drapes behind which street melodrama lurked, but here on a Midlands motorway they are murderous.

We cruised northwards to the scene of Monday's 'fatals'. Observing protocol, Sergeant de Vos radioed ahead to Derbyshire police. In a clear patch, drivers were seldom exceeding 65 to 70mph in the fast lane, but in many cases 'bunching' dangerously. Only a few had rear foglamps switched on.

'Ninety per cent of the road-users are Mr Average and Mrs Decent,' he said. 'Some are toe-rags.' We passed a buckled section of central barrier. 'A lorry did that,' he said. 'One of three on Monday which duplicated a series of accidents on the same stretch last February. Heavy lorries tend to pick up speed here.' A mile on, he nodded towards more debris on the southern carriageway's frosted verge: 'Pile-up number two.' Another mile revealed more rubble: 'There's the other one. Derbyshire get it rough.'

We were in thick, sulphurous fog. The sergeant said the smell came off spoil from coal mines, mingling with the opaque curtain often thrown up at this time of year by the flat, marshy land on either side of the River Trent. 'This is one of the most dangerous places,' the sergeant said. 'We're between junctions 29 and 30. Speed at this moment should not be above 40mph.' He left the motorway, returning south via an overpass.

Back on his own territory, he lost a fast-lane Ferrari in a fog-bank. Pursuit was dangerous. The Vauxhall Senator slowed, then slid on to the soft shoulder as traffic came to a stop. Had the Ferrari crashed?

The police car purred forward on the soft shoulder. A Volvo estate and Vauxhall Cavalier had collided. Sergeant de Vos called headquarters and reported 'an RTA' (road traffic accident), giving time and position. He talked to the drivers and took notes. Within minutes he saw that motorway maintenance men had closed a section of the fast lane to replace a damaged central barrier section. He asked them to postpone the work. 'It's crazy in this fog to close the lane and cause a tailback. That's what led to the accident.'

His radio squawked as we pulled into the Granada service area. Derbyshire had reported a 30-vehicle pile-up on the southbound carriageway near junction 30 - where we'd been just an hour earlier. Passengers were pinned down in their wrecked cars. Fatalities were suspected (there were none). In the restaurant we heard of a second pile-up on the northbound carriageway. This, it seemed, was caused by motorists who stopped to gape at the southbound accident. 'They do that all the time,' the sergeant said.

'The other day, a Chinese couple stopped in the middle of the motorway to take pictures of a crash on the other side. There are some funny people out there. A woman six-months pregnant was in an accident and asked me to baby-sit her Yorkshire terrier until she got out of hospital. I looked after it for a week - it was no trouble and sat under my office chair without complaint. I stayed with another woman who broke down until help arrived, and she asked me to radio a message cancelling her hair appointment. I stop short of that kind of assistance.'

Recently, he received an urgent call about a car being driven up the motorway with a woman's body half-in, half- out of the boot. He discovered that the 'victim' was in the boot holding down the re-set button of a faulty automatic fuel cut-off device.

In the deserted restaurant the troubled manager lamented the driving standards of his prospective customers. As he spoke, a tense man, his trembling wife and two shocked children, stumbled in, survivors of junction 30. 'We were in the thick of it,' the husband said. His wife wailed: 'It's sheer madness back there] What's wrong with people? We missed death by inches. God, we're lucky]'

'Aye,' said Sergeant de Vos.

(Photograph omitted)