Gordon Brown's chances of holding on to Labour's seat at the Glenrothes by-election lie in the hands of a man who has never ventured into politics before, never canvassed on a doorstep, never pushed a leaflet through a letter-box and never had to stand up to the ferocious attention of the media. But there is something about Lindsay Roy, Labour's candidate, that suggests that this 59-year-old teacher may yet prove to be the big surprise of the campaign.

As headmaster of Mr Brown's old school, Kirkcaldy High, he is used to dealing with trouble. There is something of the traditional Scots dominie about him — that legendary figure who struck fear into his classes, and could silence a cheeky youngster at 50 paces. His handshake is iron-like, his gaze steely, his response to questions direct and uncompromising.

As he strode the streets of Glenrothes this week in search of votes, you got the impression that the good folk of this Fife town were in for a taste of some old-fashioned discipline.

Mr Roy has been a Labour supporter most of his life, but his reputation rests on the 18 years he spent as headmaster of the neighbouring Inverkeithing High School, where an inspector's report paid tribute to his “exceptionally strong and dynamic leadership...his clear vision for the school...his capacity for leading by example”.

So highly was he rated that the SNP, which runs the local council with the Lib Dems, brought him in to turn round the fortunes of Kirkcaldy High, which had fallen on hard times. By a nice twist, he is facing, as his opponent in the by-election, the man who appointed him — Peter Grant, the Nationalist leader of the council.

So why abandon the relative safety of the classroom for the perils of the hustings? “It was an agonising decision,” he admitted. “But I reasoned that I had had some success with young people, and this was an opportunity to make a difference to a wider constituency. I've been disappointed by the way Gordon Brown has been treated. He is, in my view, a safe pair of hands and he has been falsely imaged by the media.

“I think he did very well at the conference. He's a strong leader, with good judgment, and there's no one better placed to take us through the next 12 difficult months. This notion that he is dithering is wrong. He simply gives himself time to think things through.”

That view of Mr Brown is not shared universally in the constituency. This was once a mining community — even the towns reflect that, with names such as Coaltown of Balgonie and Coaltown of Wemyss - but these days mining is mostly history, and old ties with Labour have fallen away.

Mr Brown still garners some personal support as the local boy made good, and most people feel that he gave a good account of himself in his conference speech. But what counts against him is that he happens, inconveniently, to be the leader of a party that has lost its reputation.

At any other time, a seat held by Labour with a 10,664 majority, next door to the Prime Minister's constituency, would be rock solid. But when, two years ago, the Lib Dems stole Dunfermline and West Fife in Mr Brown's backyard, despite his personal involvement in the campaign; when, at the Holyrood election last year, the SNP took Central Fife, grabbing a toehold in solid Labour territory, while the Nationalists, with the Lib Dems, took control of the local council; and when, in July, Glasgow East's 13,000 majority went up in smoke, the odds against the party began to stack up.

Time after time I came across voters who would be instinctively Labour normally, but who were hedging their bets now. That view was put most succinctly by Tom McLaren, a retired taxi-driver, outside the Kingdom Shopping Centre, as customers trickled in to take advantage of the autumn sales. “I thought his speech was quite good,” he said, “but Labour has been saying those things since 1997. They talk of change but things haven't changed, and we're living on the edge of a disaster. History tells us that every government, sooner or later, has had its day, and that's what's happened to Labour. Things are going the SNP way now.”

That is certainly the way Peter Grant sees things. He believes that Labour's 51 per cent share of the vote last time, is soft enough to melt away, and that the SNP will take the seat, helped by concerns about fuel prices, rising food costs and general disaffection with a Labour Party still struggling to forge an identity after its shattering defeat at Holyrood.

“I think people concede that Gordon Brown is doing his best,” he said. “Fifers by their nature tend to feel sorry for someone who is down on their luck. But they don't think he's done a good job as Prime Minister.”

That was certainly the view from the shoppers at the Kingdom centre. From housewives with their shopping carts, to teenagers larking about in the precinct, to elderly men who could remember the days when to question Labour values was to question holy writ, the mood was one of disaffection and distrust. Most were prepared to concede that the Brown speech had been a success, some to say that they approved of his role as Chancellor, but, when it came to committing themselves to support his party, the silence was eloquent.

The only doubt I encountered arose from the possible size of the Lib Dem vote. Their candidate is a long-serving stalwart, Harry Wills, whose political memories go back to the 1974 election when he helped to oust the Tory Teddy Taylor from Glasgow Cathcart. He points out that, with Sir Menzies Campbell holding the seat to the north and Willie Rennie the seat to the south, this should be prime Liberal Democrat territory. But the SNP is on a roll in Scotland, and few would bet against it racking up another victory.

Back at Labour's headquarters, electoral registers were being analysed and databases compiled. The party is anxious to avoid the muddle and confusion that characterised its failure in Glasgow East.

Rumours that Frank Roy, MP for Motherwell and Wishaw, who was to have led the campaign, had walked out after finding that his job was being done by a fellow MP, Nigel Griffiths, are denied angrily. But Mr Roy is no longer involved, and the role is now filled by Gordon Banks, MP for Ochil.

Everything, it seems, depends on the headmaster. As he tramped the streets in the Glenrothes gloaming, he exuded an air of calm selfconfidence. “You see,” he said, “people here know me. I've taught their sons and daughters. They have a certain respect for me.”

Gripping me bone-crunchingly by the hand, he looked me in the eye and declared: “It's time to stand up and be counted.”

The candidates

Lindsay Roy, Labour

The headmaster of Gordon Brown's old school, Kirkcaldy High, Mr Roy, left, is a friend of the Prime Minister. He is also a lay inspector of schools and a CBE

Latest poll rating 43%

Peter Grant, SNP

The leader of Fife Council, Mr Grant, top, trained as a teacher and held several positions in public finance before becoming involved in politics

Latest poll rating 43%

Harry Wills, Liberal Democrat

Mr Wills, centre, has been chief executive of several companies. He stood twice unsuccessfully for Glasgow Cathcart in the 1970s

Latest poll rating 8%

Maurice Golden, Conservative

A former student leader, Mr Golden, bottom, stood unsuccessfully for Central Fife in the 2007 Scottish parliamentary elections but increased the Conservative vote

Latest poll rating 5%

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