The sale will take place in their Edinburgh rooms on October 24 and 25.
Hensol, built in 1822 in the Tudor Gothic style, was once home to the famous big-game hunter Dick Cuninghame, whose clients included President Roosevelt, the future George V and the King of Sweden.
The sale will include many souvenirs of his early 20th century African adventures, including an archive of photographs and memorabilia estimated at £5000-7000.
Successive generations of owners have added to Hensol's treasures. Also being offered, with an estimate of £15,000-20,000, is Lerwick in the mist, a landscape by Stanley Cursiter, who played a major role in the founding of the Scottish National Gallery of Modern Art.
Summer flowers in a blue and white vase by Sir William George Gillies, estimated at £10,000-15,000, and a first edition of Joseph Hooker's Himalayan Plants, published in 1855 and offered at £4000-6000, will be accompanied by a very rare Roman banded alabaster trapezophoros terminal dating from the 3rd century AD, which comes with a guide of £8000-12,000.
The sale follows the death of Lady Catherine Henderson, who lived there with her husband, Sir Nigel Henderson, for over half a century.