Richard Dadd: Beyond Bedlam at the Royal Academy: These hallucinatory wonders are truly, madly brilliant

Is there a weirder modern painting than Richard Dadd’s The Fairy Feller’s Master-Stroke? There’s the hypnotic swirl of the structure — dotted with daisies — behind a barricade of stems. There’s the preposterous miniaturisation of the fairy world, for the action centres on the cracking of a hazelnut to make a carriage for the fairy Queen Mab. There is the scattering of monstrosities among the little folk — the couple with heads squashed into their necks; the strange old man under the earthen…