Some union leaders take on a faint grey tinge around the gills and a certain grim set of the jaw when trouble looms, but Mr de Gruchy just becomes more shiny and irrepressible. He proclaimed cheerfully during one early-morning phone call that he had been on the go since five and expected to carry on at the same rate until midnight.
Last week marked the climax of a campaign which Mr de Gruchy's union, the National Association of Schoolmasters and Union of Women Teachers, has been waging for some time. The union has long taken the line that difficult children should not be in mainstream schools: "I'd rather see them on the streets wrecking cars than in the classroom wrecking lessons," its leader once memorably said. But since April this year, there have been a string of cases in which its members have threatened to strike if an excluded child was returned to school after an appeal.
There was the case of 13-year-old Richard Wilding at Glaisdale School in Nottingham, now being taught at home and in a special unit. There was 12-year-old Gram Cram, who ended up being taught in isolation. Matthew Wilson, aged 10, was offered individual tuition costing pounds 14,000 after a similar row at Manton Primary School in Worksop.
Then there was The Ridings - Nigel de Gruchy's finest hour, as some commentators have claimed. Trouble first blew up at the school in March when 13-year- old Sarah Taylor was excluded after a fight with her boyfriend, by whom it now turns out she was pregnant. Staff at the school threatened to strike after her mother won an appeal, and she was withdrawn from the school. But a couple of weeks ago the staff announced that they were still desperately unhappy, claiming that there had been three serious assaults along with stone- and firework-throwing incidents.
De Gruchy spotted an opening. He sent in what he calls the "A Team" - himself plus the union's president, Peter Cole, along with the local executive member and the local full-time official. The arrival of these four should strike fear into the heart of any chair of governors. It means a strike is in the offing.
And so it was at The Ridings. The results of the union's ballot at the school, due on Tuesday, will certainly show that staff are prepared to leave their posts if a large number of children are not removed.
Mr de Gruchy has really gone out on a limb this time. One child is relatively easy to deal with, but 60 is a different matter. The Ridings is a school already close to collapse, and an all-out strike by its staff could lead to victory for no one.
So what drives the ambitious 53-year-old general secretary? Thinner than the traditional union leader and with considerably more energy, this besuited figure fits few stereotypes. His colleagues say they do not feel they know him well.
One fellow teachers' union leader who has met him regularly over the past decade says: "I wouldn't really claim to know Nigel at all. I have had very, very few personal conversations with him. I suspect that he is probably a very difficult person to know."
Despite his affable air, others confirm this view. Many people who have worked closely with him, for example, are probably unaware that he is a practising Catholic.
"I am a very quiet Catholic," he says. "I hate preaching to people, and I hate it when politicians preach to us. It makes me feel uncomfortable."
However, his Catholic upbringing must surely have left its mark on his philosophy, along with some other aspects of his childhood about which he rarely talks.
BORN and brought up on Jersey, Nigel de Gruchy was the fourth of five children. He spent the early part of his childhood in a comfortable home in the wealthy St Brelades area. Jersey was still under German occupation when he was born in 1943 and he remembers being told by his mother that he would be "sent to Germany" if he was naughty.
But a few years after he started his education at a school run by the De la Salle Christian brothers, the family ran into financial problems and were forced to move into accommodation in a disused convent. His father had lost his job in insurance and, although they were eventually able to afford a cottage in St Mary, the affluence of his early childhood never returned.
De Gruchy admits that the impoverished adolescence which followed must have fuelled his desire to do well in life.
"We were very poor. I can remember literally not having enough money to buy food," he says.
He was 12 when he first displayed the stubborn streak which must have served him well in more recent years. His parents wanted him to follow his two brothers to France to train as a priest, but young Nigel had other ideas.
"I just wasn't having any of it. I said if they put me on the boat I would jump overboard. After that, they decided I wasn't cut out to be a priest," he says.
But despite these traumas, he did well at school, often coming top of the class though he did not think of himself as intelligent. He jokes that if he had not passed his A-levels he might have been a millionaire by now: the only alternative to university for bright, young men from Jersey then was banking.
De Gruchy had already left home when his father walked away from the marriage and disappeared for two decades. The two men did re-establish a relationship before the elder Mr de Gruchy died in 1993, and Nigel bears him no ill-will. "I was perplexed rather than angry," his son says now. "We didn't talk about those things much."
Nigel's first challenge to the education authorities came when he arrived at Reading University to find that the economics and philosophy course for which he had applied had been cancelled. All his fellow freshers were persuaded to take a different degree, but de Gruchy dug his heels in and ended up taking his course alone.
After graduating with a 2:2 - "I don't think I was ever first-class material but if I had drunk a bit less I could have had a 2:1" - he spent a year in Spain and two in France teaching English, during which time he met his American wife, Judy. The couple had planned to go to the States, but the Vietnam draft made the idea less attractive. Instead, they settled in south London, where de Gruchy became head of economics at St Joseph's academy, an inner-city grammar school run by the De la Salle order. He was a disciplinarian, he says. When people ask him where he taught he replies: "Standing up at the front of the class," placing himself firmly alongside the traditional, whole-class teachers who have no truck with progressive methods.
No sooner had he started teaching than a pay dispute over a Labour-imposed "pay norm" blew up. Not instinctively political - he has never been a member of a political party - he decided to join a union, and doggedly grilled the different reps on what they stood for. The National Union of Teachers had accepted Labour's 3.5 per cent, while some unions were sticking out for more. He joined the NAS. His stubborn militancy emerged at local branch meetings where, he says, he would be the one calling for "mass strike action tomorrow"; within months he was Lewisham secretary of the union.
By 1975, Nigel was NAS London secretary and a member of the national executive. It was a hectic year for the de Gruchys, he says, marking also the birth of their only son, Paul. Judy made time to bring up the boy, while Nigel continued to climb up the ranks of the NAS (now merged with the Union of Women Teachers and claiming a membership of 160,000), finally becoming general secretary in 1990.
His philosophy as a union leader has been straightforward. Education may be important, but the NASUWT exists first and foremost to support its members' interests. De Gruchy says this approach can be in the interests of the children - the successful 1992 boycott brought on by testing and national curriculum overload led to a much-needed slimming down of the whole system, he argues. But the bottom line, in stark contrast with the NUT's more altruistic attempt to enter the curriculum debate on educational grounds, is that teachers' interest are paramount.
And this is also his stance on The Ridings. If pushed, de Gruchy will say that the interests of the pupils in question would be better served by them being placed in special schools. But for most of the time his rhetoric is much more extreme.
"There may be 15,000 children a year expelled but there are also probably 150,000 who deserve to be. Maybe we can't leave such pupils in limbo but I don't want the majority of children and teachers to be left in hell," he said recently.
So, is de Gruchy planning to follow Tony Blair down the path of moral outrage and family values? His rival union leaders do not think so. They think this is all about a fierce battle for members which all the unions claim to be winning.
"The question I always ask myself about people is, 'What would they go to the stake for?' I'm not sure I know with Nigel," one of them comments.
De Gruchy himself offers a simple explanation. "Put crudely," he once said, "pupils don't pay subscriptions. Members do."Reuse content