The couple founded the Landmark Trust, the charity that rescues and restores quirky and historic buildings for holiday lets, in 1965.
Sir John, who died aged 83 in 2007, and his wife Christian, who died aged 91 in October 2018, are credited with the rescuing of a number of significant historic buildings around the country.
The trust, now with 200 buildings in Britain and Europe, paid tribute to the couple when Christian died last year and wrote: “While Sir John Smith’s genius and generosity made Landmark possible and saw the salvation of scores of special buildings, it was Lady Smith’s touch and taste that made the buildings themselves such delightful places to inhabit.”
Sir John, a businessman and philanthropist, was from a prominent family of bankers and a descendant of 19th-century travel pioneer Thomas Cook who founded the travel agency Thomas Cook & Son.
Among the items coming up for sale is an English School, 1810, portrait miniature of Oswald Smith. Smith was an English banker and Conservative Party politician who sat in the House of Commons from 1859-80. Measuring 2.75 x 2in (7 x 5cm), it is estimated at £400-600.
Sir John campaigned to restore the Royal Naval ship The Warrior and following its multi-million-pound restoration it was handed over to the Maritime Trust in 1979. A 2ft x 2ft 6in (61 x 77cm) oil on canvas depicting The Restoration of 'The Warrior' at Hartlepool by Stephen Crowther (1922-2007) is estimated at £500-700.
A Victorian oval locket decorated with a cross in diamonds and children's teeth, with a blue enamel border in a fitted case, is estimated at £100-200.
The sale is held as part of Chorley’s summer country house sale on July 23-24.