WHAT is "normal"? "Normal is a setting on a washing machine," the fridge-magnet motto runs. As a means of describing human behaviour, the word has been in the English language only since the early 19th century; and Dr Johnson, the lexicographer who might now be diagnosed as having Tourette's syndrome, would not have understood it as describing a state from which he deviated so brilliantly.

The current terminology is "neurotypical"; and it was in celebration of neurodiversity that Bridget Kendall gathered her guests for last week's The Forum (Radio 4, Saturday). So much is about context: in the halls of academia, an absent-minded professor is just one in a crowd, although there might be a plethora of diagnoses that he might like to lay claim to, other than mere eccentricity.

Indeed, it was in discussion of diagnosis that this programme became particularly interesting. Professor Ute Frith, a pioneer in research into autism, admits that OCD, Asperger's, and autism are regularly used as a way for people to excuse their fears and foibles. And she should know, since her other expertise is dyslexia, a condition that, if all the diagnoses are to be respected, has become a plague.

The Indian novelist Jerry Pinto, whose book about living with bipolar disorder is having some influence on the way people in his home country view neurodiversity, is more happy with diagnoses that give the individual some means of owning the condition and presenting it to the world. Once somebody labels you mad, there is nothing you can do or say that will make you un-mad in the eyes of others.

If academia is one environment where eccentricity is expected, another must be the world of celebrity and the wealthy. A diagnostic assessment of Leonard Plugge, featured in Archive on 4: The eccentric entrepreneur (Radio 4, Saturday), would rob this extraordinary individual of much of his charm, and also excuse his faults.

Plugge was the proto-radio pirate, broadcasting from France to English audiences during the '20s and '30s programmes that the Presbyterian John Reith thought unsuitable for British listeners. When on Sunday the BBC was broadcasting How to Read an Epistle and Heroes of the Free Church, Plugge's Radio Normandy provided dance-hall music, fronted by no less than Roy Plomley, later of Desert Island Discs fame. Carrying adverts for everything from Persil to Bile Beans, Plugge made a fortune - and he needed to, in order to support the Gatsbyish lifestyle that he cultivated for himself.

A pirate, perhaps; but not a cowboy. Plugge took a nerdish interest in broadcasting engineering, touring Europe to look at transmitters, and becoming an expert on the emergent technology. But it was his eye for an opportunity that made him, including stunts such as a fashion talk sponsored by Selfridges, from the top of the Eiffel Tower.

He was also a rogue; and, according to his son, not always a lovable one - his flirtations extended to his son's girlfriends. Had the war not intervened, and Plugge's stations in France shut down, we might now be revering a very different father-figure for British broadcasting.