In a quiet corner of north Lincolnshire, not far from the Humber Bridge, is a modest country house standing in a modest park with a genuinely extraordinary art collection. Scawby Hall, near Brigg, does not look as if it holds the key to one of Britain’s most important painters but its family were the first patrons of the master equine painter George Stubbs, whose paintings adorn the National Gallery. For the past 15 years, Scawby has been home to Tom Sutton Nelthorpe and his wife Kristin – a former financial journalist and Wall Street lawyer respectively – and their three children, two dogs, and two cats. The house has been open in a “fairly low-key way” since about 2008, but this summer they are putting on more open days and guided tours to mark Stubbs’ tercentenary. For if Scawby is known for anything then it’s Stubbs. The Nelthorpe family has been at Scawby since 1603, when Richard Nelthorpe began building a house on the site. In 1620 he bought the Baysgarth estate, 15 miles away at Barton-upon-Humber, where the main branch of the family lived until 1792, when Sir John Nelthorpe, the 6th Baronet, made Scawby the main family residence....