One afternoon in autumn 1949, a fresh-faced junior psychology lecturer from Bangor university arrived for his first session working in a local child guidance clinic. At the top of his client list was Brenda, a 10-year-old with an above average IQ and an inexplicable inability to write and spell.

This encounter was to determine Tim Miles’s professional life for the next 50 years.

In the 1940s and 50s, a child who failed to read was assumed to be either backward or emotionally disturbed. Tim Miles had a brief flirtation with psychoanalytic perspectives himself: “At the clinic I once asked a child tentatively, ‘Was it anything to do with going to the toilet?’.” The child looked at him blankly, and he reverted to the suspicion Brenda first sparked in his mind: that bright but hopelessly non-literate children were suffering from a specific brain deficiency, something like a stroke or aphasia, that they had had since birth.

Over the next 15 years, as he rose from lecturer to professor at Bangor university, a steady stream of school-referred children turned up in his weekly clinic. He tried test after test to see where their deficiencies overlapped. We are so familiar today with dyslexia’s cluster of difficulties that it is hard to imagine that frustrating, yet intriguing, search for a map in a land of blind alleys. Brenda was completely unable to draw a bicycle or house plan. Might that be a clue? No, it turned out, after a host of bemused children handed over their perfectly normal pictures. Brenda just couldn’t draw.

But some clues did appear. In a book published earlier this year, Fifty Years In Dyslexia Research, Tim Miles describes how, believing diagnosis without treatment was unethical, he began to teach Brenda and other children to spell, inventing a system of letter-sound correspondences remarkably close to today’s phonic methods. Gradually a picture emerged of children struggling with letter sounds, memory, pattern and sequencing, until, in 1961, he published a paper called “Two cases of developmental aphasia”.

Brenda was one of the cases; the other was a boy called Michael, whose spelling was even more bizarre. In it he argued that these children had a physiological deficiency which might understandably give them cause for anxiety or disturbed behaviour. It was accepted for publication, with a referee’s sceptical proviso that it should make clear “this kind of thing is extremely rare”.

By then a handful of other researchers were interested, among them Professor Margaret Newton at Aston university, and Alfred White Franklin, an enlightened paediatrician at Bart’s Hospital in London, who had come to believe that the stomach aches and school refusal he saw among child patients was linked to their inability to read and spell.

In 1962 Dr White hosted a conference, inviting professors Miles and Newton, and a host of other educational and psychological experts. The outcome was a Word-Blind Centre, set up in two caravans in Coram Fields (the precursor of the Dyslexia Association and Institute), and a storm of controversy.

Heads and teachers were cautious about the idea of dyslexia but supportive once offered effective teaching methods, he says. But education planners, spenders and, above all, psychologists, says Professor Miles, were infuriated by the implication that they had missed or misinterpreted this syndrome. Some argued that labelling it organic implied it was incurable; others that it would open up education to insatiable parental demands. Such a heady mixture of high principle and wounded pride led to more than 20 years of “venom and hostility”, he says. “There was lots of resentment.

Feelings were very bitter.”

At the same time the discoverers of word-blindness (the term “dyslexia”

came several years later and aroused still more opposition) felt they could not “stay in the academic clouds”, says Professor Miles: “Word got around among parents that you could get a dyslexia assessment at Bangor or Aston.

Parents at the time really were desperate, they travelled from all over the place saying ‘Would you look at my child?’. We had to get involved, because these children were suffering. Then they’d get the help they needed.”

Of course, the parents who could travel for an assessment were the middle-class ones, hence the next hostile analysis: that “dyslexia” was a middle-class smokescreen for “thick”. Prevalence studies carried out by Professor Miles in 1980 showed that, if anything, dyslexia was more common among working-class children.

“We were seeing children from the slums of Caernarvon. We knew they weren’t middle-class.” But it took until the 1990s, with the widely reported study of huge numbers of dyslexics in prisons, and then the identification of a genetic marker in the DNA of parents and children with dyslexia, to finally lay that claim to rest, he adds.

Even now, as he looks back on 50 single-minded years, he says: “Provision for dyslexic children is very patchy today. In some places it’s good, but there’s still suspicion about it. But I had the impression from the very beginning that we were on to something. So I had to go on with it.”

Fifty Years in Dyslexia Research by Tim Miles is published by Wiley Pounds 21.99