A party of disorderly couples has gatecrashed the Picture Gallery at Bath’s Holburne Museum, climbing on to the antique furniture, hanging off the track lighting and sprawling on the floor, putting the noses of the resident Gainsboroughs, Constables and Zoffanys out of joint. Lawks-a-mercy! What has come over the Holburne? A passel of Mrs & Mrs Popes, that’s what: 36 years’ worth, to be precise.