But her knowledge of children and what they like doing is unrivalled, springing straight from the young themselves and from what they have always liked: reading, singing, playing, chanting or bawling out. The school playground and children's informal written descriptions have been the Opies' principal data base, rather than the university laboratory or the standardised questionnaire. The freshness and authenticity permeating all their books show that children are always the best sources for demonstrating what they do.
This particular literary labour has not led to an easy life. Each book took years to produce, with social life cut right down and money a regular problem. Yet this is always what the Opies wanted to do. As entirely self-taught researchers, neither of whom went to university, Iona was the archivist for the reports gleaned from so many loyal informants or from her own observations. Peter was the perfectionist, refusing to go to bed until the right phrase had finally dropped into place.
Since his death in 1982, Iona has been in full charge, yet her next magnum opus will still come out under both their names. This will be a study of the multitude of games children play with the aid of different objects, such as marbles, five stones, balls and skipping ropes. The joint research for all this now resides in shelves of files labelled in Peter's crystal-clear handwriting. The book will take at least seven more years to complete.
Meanwhile, Iona has herself produced The People in the Playground, based on notes kept over two years while observing pupils in her local school. The emphasis this time is not simply on what the children are doing, but also on a week-to-week picture of the playground itself and its main characters and events. It is an enthralling study. Most children have at some time known both the agonies and the ecstasies of the school playground, when essential rules and pecking orders are sorted out well beyond the reaches of teachers or concerned parents.
Iona recreates the rumbustious, kaleidoscopic atmosphere of this childhood jousting area in a way that is hard to resist, however much - as an adult - one may occasionally want to suppress some of the memories of what really went on there. The more relaxed social climate of the Nineties enables her to quote the salty rhymes, jokes and insults that were impossible to print when The Lore and Language of Schoolchildren came out in 1959, when 'knickers' was quite the rudest word they were allowed to include. Today, the more robust examples she quotes would still be out of place in a family newspaper. No wonder her anxious young informants first made sure that she wasn't going to tell teacher before providing her with some of their favourite material.
The cruellest playground insults and prejudices now seem to be disappearing as society becomes more sympathetic towards the disabilities and unpopularities once so mercilessly stigmatised in playground lore. Some traditional games are also beginning to go, along with the hoops and tops formerly so beloved of the young. Singing games, too, are much less in evidence, with boys now refusing to join in these ancient survivals of courting rituals.
Yet children will always need to play, and their good humour determines that those games which replace older ones will still be noisy, occasionally disrespectful and excellent fun for most concerned. In recording all this in her latest book, Iona reveals that after years of working principally as an archivist she can also write like an angel, forever tolerant, unfussed, wise and honest.