This extraordinary double portrait has three of Rembrandt’s trade-marks: light, texture and humour. Cool daylight floods in from the left (from a window which does not appear), explaining all the forms and spaces in a composition without obvious perspective. The figures have a finely hewn presence as if the paint were moulded plaster. Their interaction is urgent, touching and slightly absurd.

Acquired by George IV in 1811, when Prince Regent