It was called the National Marriage Guidance Council until David French got hold of it. The first thing he did was change the name to Relate - something a little racier, a little more in the groove. And, not for the last time in his directorship, voices rose in dismay.

"The tabloid response," French says, "was: 'Look at them, they've dropped marriage. They no longer believe in it.' And around the Council there were a lot of raised eyebrows at this worthy part of the establishment choosing such a trendy name. The fact that it was a verb and not a noun was kind of the last straw."

That was 1987. Eight years later, David French has just announced his resignation. He claims there is no particular story behind this decision. He was 48 last month: he didn't want to pass 50 in the same job. But he also feels he has done all he can for Relate - and this may be easy to accept. It is now almost unrecognisable from the organisation he joined: last year it counselled 70,000 people, twice as many asbefore he arrived. David French isn't, one senses, much given to bragging, but even he points out: "There aren't too many businesses that have expanded at that rate." It comes as no surprise that his major area of interest while a social studies undergraduate at Durham University was, "how you effect change in big organisations".

David French can't claim the credit for this organisation's change of name. It was arrived at by a PR firm which "positively fizzed with names for us". Couples in Crisis enjoyed favour for a while, as did Marriages in Crisis. "But the debate that developed became: did we want a name that spelt crisis or one that was about relationships?"

In any case, at the point French moved in, it wasn't just marriages that were in crisis, but marriage itself. Marriage was thinking of walking out and never coming back. Couples were choosing to live together; divorces in Britain were running at 150,000 a year, or four in 10, the highest rate in Europe. Nor had the National Marriage Guidance Council adequately addressed social changes such as the changing role of women or the multi- cultural nature of society. If it had stood still much longer, it might have been washed away. "Nobody understood the concept of profile," French says, "or of getting good press coverage or funds from donors. These were things other charities did, but which you couldn't do for something as private as marriage guidance."

David French's period at Relate will be remembered for many things, but privacy is not first among them. Not that the public noise he created has always come about deliberately. Eighteen months into his tenure, he convinced the Princess of Wales that she should become Relate's patron. He had no notion that shortly afterwards she would become a potential client. This was greeted in some quarters as a massive and hilarious backfire. Mr French regarded it as the opposite - an unfortunate but appropriate underscoring of his organisation's purpose in a tumultuous age. What clearer indication could there be that marriage was going through a bad patch than the fact that the nation's emblematic family was falling apart?

The Princess has stayed in place. "She's been hugely courageous in saying, 'I'm going to go on with this',"Mr French says. He believes her support communicates important messages about Relate, "that marriages are not only sweetness and light ... that there are other possibilities than carrying on living your life in a loveless marriage." Her presence, French estimates, generates pounds 150,000 a year for the organisation.

With the Princess on board, French set about the risky business of broadening Relate's range. The adjustments were extensive. It stopped speaking exclusively of "marriages" and took up the phrase "established relationships". French made it clear that gay couples were free to consult Relate (although when I asked him if any do, he says, in practice, they don't). In 1992, he complained that television commercials "hoodwinked" people into accepting the traditional suburban family. In a speech he gave at the time in which he said: "The public is now more willing to accept that families of various shapes can and do function well - some with one parent, some with two." The Archdeacon of York jumped on him for this, declaring it "very irresponsible for a man in his position".

The publication of The Relate Guide to Sex in Loving Relationships didn't exactly go down a storm with rightwingers. Neither did Mr French's continual campaigning to amend the divorce law, which, early on, met resistance from a certain John Redwood, then a little-known Secretary of State for Wales. It is a source of pride for French that the issue Relate campaigned on - abolition of fault-based "quickie" divorces, in which one partner sues the other - was recently endorsed in the Lord Chancellor's white paper on divorce.

"We've got deeply ingrained habits about divorce being an adversarial business. There's a gut reflex: we've got to pin the bastard because he walked out on her. But probably something led to that happening. And in any event, what do you achieve by trying to pin the bastard?

"Three-quarters of divorces use the fault grounds because it's the quickest way. So one of the partners finds themselves on the receiving end of a catalogue of their misdemeanours, drawn up by a solicitor and often unsubstantiated, containing things that the partners have never said to each other. We pick up the pieces of couples who were prepared to set about ending their marriage in a reasonably adult way, but the law intervened and created divisions between them. And all this is in the face of research which agrees that the best environment for children is one that is free of conflict."

French has also argued for the legalisation of re-marriage in church, another issue not likely to endear him to the right. He argued for it in the unlovely language in which counselling agencies tend to express themselves in public. In a letter to this paper, for example, in 1994, he wrote:"Men and women continue to seek and need a lasting commitment to one other person as the baseline from which they can manage their relationship with a complex and changing world."

If the terms in which this was expressed smacks of committee-speak, of the bleak realms of the efficiency report and the human resources strategy, then this only tallies with a view that French still holds: marriage is a "thoroughly practical arrangement" - good business sense. He is quick to stress that that's not all he thinks it is. It's just, he believes, the aspect of marriage - or rather, of established relationships - with which Relate can most effectively busy itself.

"The assumption that Relate only works with married couples is not really out and about any more," he says, understating the case. "We very much believe in marriage. We also recognise that people make choices outside marriage. But that doesn't mean that marriage doesn't have a socially useful purpose, which it clearly does. Most adult couples still get married. A very high proportion of people who get divorced get married again."

When I met David French, it was not at Relate's functional head office in Rugby but at a lavish Victorian hotel with its own rolling and sculptured grounds in the Hampshire countryside. He was in the middle of a four- week conference run by the Cabinet office under the title, The Top Management Programme. French and a number of other high-flyers - a sales director for British Airways, a lawyer in the Department of Trade and Industry, someone from Taylor Woodrow - had gathered to hear lectures, form discussion groups and give talks. "Everybody's learning a great deal from each other," he assured me, as we adjourned to the sunny garden beside the croquet lawn.

For all the modernising, there's at least one sense in which David French has put Relate back in touch with its founding principles. "It's interesting if you look at the original 1938 constitution," he says. "It's all about education and research and it doesn't say anything about counselling, whereas more than 90 per cent of Relate's work today is counselling." In October 1993, Relate established a research unit at Newcastle University - the Relate Centre for Family Studies. Later this year, the Centre will report on marriage in the 1990s and Relate's own work.

"The study is going to ask: 'Do we make a difference?' Not only in the sense of whether couples stay in their marriages after coming to see us. This is a false assumption people have, that we have an objective to put marriages back together again. We don't have an objective other than to provide a safe environment in which couples can make that choice for themselves. The unduly vocal, right-wing lobby has tended to deduce from that that we're indifferent, but this is absurd. If a couple leaves us together and happy, then that's a result. If they leave us apart but less unhappy, that's a result, too."

French's own parents had, he said, "a marriage as happy as it was possible to imagine. I was terribly lucky in that respect." He grew up in west Dorset. His father was a naval officer who had joined up at the astonishingly young age of 12. He was also a devout Christian. "I didn't grow up with his single-mindedness," French says. "The only thing I was single-minded about was that I didn't want to be a naval officer. Luckily I had a brother who did and family honour was satisfied. I grew up surrounded by the navy and it was quite hard for me to establish what other kind of identity was possible."

After graduating, he worked in the brewing industry and then headed off into the voluntary sector. He had jobs with the National Council of Voluntary Organisations, the Royal National Institute for the Deaf, and the Children's Society. He then became director of what was yet to be known as Relate. "I suppose there is a path here: from working with children who had the experience of family breakdown somewhere in their past, to working with the family breakdown itself."

Of course, the question one most wants to ask David French concerns his own marital status. It would satisfy some media and political characterisations of him to learn that he lived in a tepee in Wales and enjoyed a variety of loosely sanctioned relationships within a community of virility worshippers. Sadly, perhaps, this is not the case. He responds to the question crisply - in the manner of someone who gets asked it a lot. "I'm married," he says. "I'm married to my first wife. I'm happily married. And we have four children."

He is still, to some extent, a sceptic. "There never was a golden age of marriage," he says at one point. "People talk about going back to basics. There are no basics to go back to in this field." But, for his own part, he confesses, "I think a public statement is very much part of the deal."

He was married to a bishop's daughter in Carlisle Cathedral by his godfather, "a clergyman who had a wonderful sense of the dramatic. When we got to the line, 'Those whom God has joined together let no man put asunder', in a way which took most of the congregation by surprise and in a manner quite at odds with the way he'd conducted the rest of the service, he simply boomed this at the assembled company. It had a particular effect because around the galleries of the cathedral were members of the public who had turned out to see the bishop's daughter married, and one had the sense that the clergyman was talking to the world as well as the people he was marrying."

This recollection prompts French to reflect: "There's nothing left of the institution these days other than the way in which it fulfils people's individual needs and expectations."

He sounds slightly rueful as he says it. A traditionalist after all, perhaps.