A 1920s oil painting of a wealthy American heiress, Ruth Brady, who later owned a historic Wiltshire house is set to fetch more than one million pounds at an auction in America next week.

The picture, titled Portrait Of Miss Ruth Brady On Bugle Call, was painted by Sir Alfred Munnings in or around 1927, the year in which Miss Brady celebrated her eighteenth birthday.

It is expected to sell for between £1 million and £1.4 million when it goes under the hammer at Sotheby’s in New York on Wednesday.

The picture most recently changed hands when it was sold at Christie’s in London on May 20, 2005, fetching £1,486,400.

On New Year’s Eve, 1928, just a few months after the picture was painted, Ruth Brady, daughter of multi-millionaire New Jersey financier James Brady, married British aristocrat Michael Simon Scott.

In 1934, the Scotts bought Stockton House at Stockton, near Codford, now a Grade I Listed house, and planned to make it their base in England. But four years later, on February 4, 1938, Mr Scott tragically died, at the age of 37, in unusual circumstances.

According to his obituary in The Times newspaper, he “collapsed and died in a boat off Palm Beach, Florida, after a struggle of half an hour at the end of which he succeeded in landing a sail fish”.

His wife, Ruth, remained the owner of Stockton House until 1950, when she sold the house to a local farmer, named JM Stratton, who kept the farmland near the house but, in 1951, sold the house to Lady Lacey.

Michael Simon Scott was the first cousin of wealthy Scottish landowner and 24th Chief of Clan Fraser, Lord “Shimi” Lovat (1911-1995), a colourful and much-decorated Second World War hero and commando, who took part in the D-Day Landings in Normandy on June 6, 1944, and who was later portrayed in the 1962 Hollywood movie The Longest Day, by Peter Lawford, who was also the British brother-in-law of US President John F Kennedy.

Mr Scott bought Stockton House, Stockton, from Oswald Toynbee Falk (1879-1972), a stockbroker and economist and close friend and business associate of economist John Maynard Keynes.

Mr Falk, affectionately known as Foxy, was also rumoured to be a lover of the legendary Russian ballerina, Anna Pavlova.

To help maintain Stockton House in the late 1920s, Mr Falk employed a chauffeur, five maids and seven gardeners.