In 1972, Roger Cardinal wrote a book intended to bring to an English-speaking audience the French concept of art brut – literally “raw” or “uncooked” art – a term coined by the painter Jean Dubuffet to describe the work of the neurodiverse, then labelled more baldly as “mad”, eccentric or unworldly. Cardinal’s own preference, as a book title, was to leave the term as it was. “You’ve got art nouveau and art deco,” he reasoned with his publishers, “and now…