Sean O'Grady: Meet Motorway Man, the decisive voter in Election 2010

He is in his thirties. He drives. He voted Labour in 1997, and has a small family

We've had the C2s, Essex Man, Worcester Woman and Mondeo Man; now meet Motorway Man. He and his family are about to decide the fate of the nation. Tory researchers have identified him, and the marketing company Experian apparently came up with the catchy name. We will be hearing a great deal more about him as we near polling day.

He lives in the concentration of marginal constituencies along, and bounded by, the M1 and the M6, a psephological golden triangle. The corridor runs from around Junction 13 of the M1, with the two Milton Keynes seats, and runs up to Morley near Leeds on the M1 (Ed Balls's seat), and Chorley on the M6 (Junction 27) – large clusters of swing seats around Leicestershire, Staffordshire, Derbyshire, Cheshire and Lancashire.

MM's parents might have worked in one of the great old industrial cities there, but he's moved out to somewhere nicer and roomier, maybe on land reclaimed from mining or other heavy industrial use. He favours those modern private estates, and probably, for the moment, occupies a semi, though he aspires to the full detached residence he believes he deserves.

As his name implies, he may well drive a mid-range family saloon or people-carrier, or both, and will spend a good deal of his time pounding Britain's motorways in his job, like the "reps" of a previous age. MM is in his thirties and he may not have built up that large a cushion of equity in his home. He will have a small family. He is not so wealthy that he can afford to send his children to private school, so he uses the state system, which will be better than in, say, inner London, but he will have issues about it, as he may well about the NHS and the social care offered to elderly relatives.

His political allegiances are loose, and he voted New Labour in 1997. He likes the web, foreign holidays and going to the gym. Motorway Man is someone the politicians are extremely keen to befriend. It is towards him, for example, that the Conservative deputy chairman, Lord Ashcroft, is said to be targeting the funds he has made disposable to the party.

At first glance it looks like the Labour party might as well not bother knocking on his neo-Georgian UPVC door. A recent YouGov poll gave Labour just 27.5 per cent support among Motorway Men, with the Tories on 43.5 per cent. He's in fact been leaning the Tory way for a while; But five years ago they had a smaller lead – 31.7 per cent to 27.6 per cent, for what was still Tony Blair's Labour Party.

There seems to have been a bit of a squeeze on the Liberal Democrats – not that surprising as they never prosper in Tory-Labour marginals. But not welcome news for a party that might have dreamed of breakthrough among people who, at least superficially, ought to warm to Nick Clegg, a leader about their age and with the same pragmatic outlook on the world.

Still, it is Labour that ought to be really worried. If you could have imagined a set of polices, or economic outcomes that could be aimed like an exocet missile at the wallet of Motorway Man you could not have done worse than what Labour has presided over for the last couple of years.

The holiday in Florida or France is getting expensive. The value of his home has plummeted, and, before long, his mortgage bills will be going up again, as has VAT and his income tax and national insurance (and again in April). And every time Motorway Man fills up his Vauxhall Insignia he will feel the pinch and wonder, to borrow a phrase, if things can go on like this. The Office for National Statistics said on Tuesday that the cost of motoring is up a fifth on this time last year, with petrol prices, garage bills and the cost of new and second-hand cars going through the roof.

He may or may not listen to Alistair Darling and George Osborne arguing the toss about withdrawing the stimulus early, but for a man who spends most of his time viewing the world through a car windscreen the more general "war on the motorist" feels more immediate. There may be valid green arguments for driving up the cost of personal transportation – which he will acknowledge – and he might even accept that speeding is a bad idea, but everywhere Motorway Man drives or tries to park he will feel the unforgiving, vindictive and costly presence of speed cameras and rip-off charges.

It is not, at any rate, likely to place him in a pro-government mood, and I doubt that even Gordon Brown (who doesn't drive) at his most panicked will order the removal of every speed camera in Britain. It'd be a great way to win an election though.

s.ogrady@independent.co.uk