Grimsthorpe Castle is a country house in Lincolnshire, England 4 miles (6.4 km) north-west of Bourne on the A151. It lies within a 3,000 acre (12 km2) park of rolling pastures, lakes, and woodland landscaped by Capability Brown. While Grimsthorpe is not a castle in the strict sense of the word, its character is massive and martial – the towers and outlying pavilions recalling the bastions of a great fortress in classical dress. Grimsthorpe has been the home of the de Eresby family since 1516. The present occupant is Jane Heathcote-Drummond-Willoughby, 28th Baroness Willoughby de Eresby, granddaughter of Nancy Astor, who died at Grimsthorpe in 1964.

Bourne is a market town and civil parish in the South Kesteven district of Lincolnshire, England. It lies on the eastern slopes of the limestone Kesteven Uplands and the western edge of the Fens, 11 miles (18 km) north-east of Stamford, 12 miles (19 km) west of Spalding and 17 miles (27 km) north of Peterborough. The population at the 2011 census was 14,456. A 2019 estimate put it at 16,780.