When an American describes a woman as wearing a ‘Park Avenue Helmet’ you know exactly what is meant. This is a hairdo so precise and sculpted that it trembles, category-wise, between coiffure and armour. Both natural and artificial, it also accurately signals social status.

The link between hats, hair and caste was first made by James Laver in his 1937 classic Taste and Fashion, a book not yet bettered in its field.