LAST week at Bristol magistrate's court, sentence was postponed on Robert Hammill, 19, of Wells. Hammill had been charged with stealing a pounds 140,000 National Express Rapide coach and a coach-driver's jacket, driving while disqualified and without insurance and obtaining diesel by deception.

In mitigation, the court heard that Hammill had driven the coach 'impeccably' on a two-day, 400-mile trip from Bristol to Poole, London, Oxford and Birmingham along set routes. As he went he picked up passengers, none of whom had cause to believe that he was anything other than a professional driver.

Despite his impeccable driving skills, however, the court clearly thought Hammill to be pretty barking. In his defence it heard: 'He can only be described as a frustrated coach-driver who has a real problem with coaches.' If he is, Hammill is only one of many.

There exists a breed of people who want to drive buses and trains, but for some reason can only fantasise about the experience. Then there are those who, in progressive stages of omnibusmania, sit on the back seats of moving buses pretending to press pedals, select gears and give signals to other vehicles. There are those who mimic the appropriate sounds to accompany the experience (ding, ding . . . gargle, gargle). And in extreme cases, there are those who actually think they have turned into buses, coaches, trains and trams.

There was, for example, a man from Welwyn Garden City who led a double life as a corporation tram, following the prescribed routes, stopping and starting along the way. There are people who can be heard puffing along pavements as if they were the Flying Scotsman.

Robert Hammill is clearly not in one of the terminal stages of omnibusmania. But what lies behind his and others' fervent desire to drive a bus or coach? What makes the need so pressing that the would-be driver is prepared to face a fine, imprisonment or even the psychiatrist's couch?

As one who has worked on the buses, first as a conductor and then, in one of those secret interstices of youthful rebellion, as a driver of a big six-wheel, 64-seat, 115-horsepower London Transport Routemaster, I feel in a position to offer clues, if not answers.

Robert Hammill would have revelled in the sense of precision and control experienced when guiding a giant vehicle safely and smoothly along crowded roads. The satisfaction to be had in driving a bus or coach does not lie in going fast - a London double- decker rarely exceeds 30mph and National Express Rapide coaches are limited to 70mph on motorways - but in travelling as smoothly as a magic carpet. Passengers should be unaware of being driven; the bus should stop gently, accelerate in one smooth surge and progress in stately fashion like a great dray horse at work.

There is also satisfaction to be had in performing a public service (to even think of such a thing in privatised Britain will soon be a criminal offence), in watching the world go by from a lofty seat, in feeling, perhaps, like the skipper of a ship. And, until London's bus network was denigrated by churlish and dogmatic politicians in the 1980s, the custom-made London buses were handsome works of practical, thorough and stylish civic engineering. Driving a London bus made you feel a part of the very fabric of this special city.

In Mr Hammill's case, perhaps he had been driven badly once too often and decided to take the wheel into his own hands. If this was the case, I know how he feels. The temptation sometimes steals upon me to leap into the cab of an idle double-decker and to drive weary Londoners home as smoothly as if they were sailing lazily through the Doldrums on board the Canberra.

Of course, he might - like the human tram of Welwyn Garden City - simply be in need of help, rather like Britain's bus and coach services themselves.

(Photograph omitted)