‘The Cardinal’ is among the most visual archetypes in European history. His rich red robes and ostentatious headgear betoken the leadership which the pope vests in him; his airs of primordial authority and sacerdotal noblesse instinctively draw the eye. Even an art historical layman can identify a cardinal immediately from the cut and colour of his cloth: scarlet, crimson, carmine, vermilion, ruby – even, as in the famous bespectacled portrait of Fernando Niño de Guevara (Plate 12), rosé – the shade of red matters not, for the association of iconography and office is so strong. Cardinals thus, ironically, would seem to enjoy a more straightforward visual identity than the popes whom they faithfully served – the pope's costume, by contrast, manifesting itself in rather more variable shades and emblematic designs than those available to his mere electors. Yet the single factor of colour has come to be so meaningful with the cardinal that it can feel as if almost the only filter through which to glimpse him. To delve deeper into who cardinals were, and why they mattered, we have to push past this primary association to interrogate the somewhat broader palette with which this extraordinarily varied group of individuals put a gloss on their lives.

Over 1,200 men became cardinals between 1417 and the end of the eighteenth century and many discharged their roles and responsibilities as porporati quite differently.