It’s a Constable – but not the one you know – in a new show of forged art

A seascape in the Courtauld exhibition that was once, but no longer, attributed to John Constable. Photograph: TBC

A Constable seascape that will hang in London’s Courtauld gallery this summer shows sailboats and a steam vessel bobbing on a choppy sea beneath one of the artist’s typical imposing skies.

Except this Constable is not all it seems. Experts at the gallery found incriminating evidence in a cut-off paper watermark, “184-”, meaning that the paper dates from at least the 1840s, years after the artist died in 1837.