I first met Jim Alexander sitting the foyer of the Russell Square Hotel in London. I had met Steve Aos from the Washington State Institute who recognized him and introduced us to each other.

"I would love to shake your hand", Alexander began, "but I think I caught something terminal on the airplane on the way over and I don’t want you to catch it".

The next day, on another chance meeting in a conference to promote evidence-based programs, Alexander took my extended hand and launched into a discussion about the interesting questions that were emerging as a result of implementing his brainchild Functional Family Therapy in the UK.

"So you are recovered from your terminal illness?" I asked him, indicating our still linked hands. "Oh that" he said. "The recovery power of the human animal is a wonderful thing. I really thought I was on the way out but after a good night’s sleep here I am, ready to rock and roll".

May be that provides a metaphor for impels Alexander – a belief that no matter how dysfunctional the family, the right treatment can create recovery. But he is also someone who, by his own admission, cannot stop his brain working things out, and over a few decades of analysis has produced a lot of results.

In one sense he knows too much. Describing FFT to potential commissioners of services on a study tour to the West Coast of the USA, organized by the Social Research Unit at Dartington in 2009, Alexander over-whelmed his audience with the breadth of his knowledge and application. But they lost sight of what FFT does. So to clarify the product I offered a tweet summary of FFT: “FFT improves relationships in highly dysfunctional families so that adolescents get along better at home and behave better in society.”

"Yes”, said Alexander. “That’s just about it. I would just add ....." And within five minutes the description had blossomed to capture the full complexity of family life and the difficult job of solving adolescent problems.

But beneath this barely controlled enthusiasm I have come to realize that genius lies. The prevention world is full of really very smart people, but few can be placed in the genius category. What qualifies Alexander for the title?

The individual ingredients are shared by most of his peers. He has the gift, like Gerry Patterson and Albert Bandura, others in the genius club, of being able to watch children and families and see what nobody else can see, until it is pointed out to them. Most of the ingredients of FFT are pretty obvious now but they were counter-intuitive when Alexander first proposed them. That comes from careful observation.

Alexander has pulled off that rarest of skills in marrying, in a single program, a systematic approach to treatment that responds to the individual needs of each child and family. Every family is unique. But there are common causes to each family’s difficulties. FFT directs the practitioner to the common cause and the each family’s particular manifestation of the problem: easy to say, extremely difficult to achieve.

He has done what all good prevention scientists have done but that most scientists and policy makers have not in rigorously evaluating his product There can be few doubts that FFT works.

I am impressed also at Alexander’s ability to let go while protecting the core of the program, the elements that must not change if the same results are going to be achieved. This, too, is a rare gift. Too many prevention scientists cling too close to what they have designed restricting its take up. Too many others have made what they have produced generally available only to see them perish for lack of care and attention. Alexander steered the middle ground.

To use his own words, Alexander has succeeded, where most of the social work profession has failed, in turning “this wishy- washy liberal social work stuff”, as he calls it, into something which is respectable, comprehensible and effective.

And, most importantly, to me, unlike most of his fellow prevention scientists, Alexander understands the individuals he is working with. Adolescents often act as if they imagine that the world is against them when, in fact, it is offering every opportunity. Alexander can work this out and sorted out the problem, for the young person and their parents.

Alexander is the sort of person troubled adolescents can respond to. He is full of contradictions, hard, empathetic, clever, whacky (a word he uses). Even those who don’t warm to him must, at least, have to take a dozen or more takes trying to work him out. And by the time they get near to an answer, Alexander will have worked out what is wrong in the adolescent’s life and be well on the way to putting it right.

Few people have any one of these attributes. But hardly anyone has them all. Alexander does. That puts him in the genius category.