MY ANTENNAE twitched the other day at an interview on the radio, in which Professor John Ashton, president of the nation's public-health doctors, pronounced that independent schools could form "reser- voirs of disease", which might lead to another outbreak of infectious disease like the measles epidemic in South Wales.

This is, apparently, because such schools are full of middle-class children whose parents refused to have them vaccinated during the MMR scare, as well as overseas pupils with unknown immunisation records.

The said schools were, predictably enough, outraged. The chairman of the Headmasters' and Headmistresses' Conference, Dr Christopher Ray, who is High Master of Manchester Grammar School, said that independent schools had close links with the NHS, and their policies were highly regulated.

Professor Ashton's tone offers a salutary reminder of an aspect of the MMR controversy which has generally been forgotten in the concern at the current measles outbreak, in which one man has died. But, first, I must declare an interest.

My wife and I did not give our son the MMR. The scare around the triple vaccine was couched in fears that it might trigger autism in a few susceptible individuals. But the later-discredited research on which the worries were based also suggested that children who had had the jab might develop a serious bowel condition, Crohn's Disease, from which our son's aunt suffers.

Moreover, his cousin had such a bad reaction to his first MMR jab that they had to admit him to hospital to do the second. And our boy had exhibited a spectacular series of allergic reactions to a variety of foods and additives as a baby. We decided to have the three vaccines administered singly. There seemed to be no downside to that.

Doctors and politicians did not agree. Separately injecting the three same vaccines would undermine the MMR public-health strategy, they said. Families would miss some vaccines, or forget to have the boosters done. To ensure that this could not happen, the Government in 1998 withdrew the importation licence for the single vaccines, leaving concerned parents with the bald choice of the MMR or nothing. Government bullying tactics backfired when large numbers of parents chose nothing, although many, like us, traversed the country, or even went abroad, to find the separate antigens.

When the single vaccines were available, MMR uptake fell, but it was matched by an uptake in the separate jabs. Only when the Government banned the separate jabs did vaccinations overall fall significantly.

The MMR controversy has been blamed on bad science and hysterical parents. But those were not the only factors. A key component was a political and medical arrogance that made a cavalier succession of inaccurate broad-brush statements - including ill-founded hints that the separate vaccines were not effective - to rebuff parents' anxieties rather than own up to the fact that single vaccines were just too untidy for the public-health strategists.

All this is now long forgotten. But, as Professor Ashton has reminded us, patronising arrogant assertions by the medical establishment live on. And then they wonder why the public does not always believe everything that they say.

Paul Vallely is writing a biography of Pope Francis for Bloomsbury Publishing.