The owners, whose forbears made the Grand Tour of Italy in 1850, were completely unaware who the painting was by until a routine valuation visit by Cheffins auctioneers from Cambridge started an investigative ball rolling.

Cheffins called in their Old Master paintings consultant, John Somerville, a former specialist at Sotheby’s, who recognised the painting as ‘Bolognese School’ Baroque, but needed corroboration for an attribution to Guercino as only one dog portrait by the artist is known.

That painting, a brindle mastiff with the Aldrovandi family coat of arms on its collar, was sold in 1972 for the then princely sum of £110,000  to the Norton Simon Museum in America where it hangs today. The Cheffins painting is of a bull mastiff, or, more correctly in Italian, a Cane Corso.