I was wondering what a fool is. But that article explains:

Fool. The very name is joyful – a childish whimsy of a pudding, all fruit and froth, which brings back memories of long days idling in the garden with an E Nesbit novel and the warm rubbery smell of a sun-bleached orange space-hopper. There's innocence in its glorious simplicity – Elizabeth David sums up its charms perfectly when she writes that, "soft, pale, creamy, untroubled, the English fruit fool is the most frail and insubstantial of English summer dishes".