Richard and Sheila Attenborough started collecting paintings over 60 years ago when they were first married, though at that time they could not afford anything valuable.
Now their collection includes works by L S Lowry, Henry Moore, Graham Sutherland, Christopher Nevison (Great War prints), Barbara Hepworth, Edward Burra, Christopher Wood, Ivon Hitchens and Ben Nicholson.
Together, the 50 lots are estimated to be sold for £2m.
A significant part of that estimate: £300,000-500,000 is due to the Lowry painting Old Houses.
The 85 year-old director and actor simply believed that it was someone else's turn to experience the paintings.
He commented "We have loved and cherished these wonderful pieces throughout the course of our lives, but in all truth, art belongs to no one, some of us are simply its temporary, fortunate and delighted custodians. Now is the moment for us to pass on these ravishing images for others to treasure and enjoy."
The collection is viewed as demonstrating a range of events and attitudes in 20th century Britain, from the First World War shown in the Nevison prints, to a new interest in the lives of the working classes in the 1950s-'60s.
Attenborough - one of only six actors who have won an Oscar for best director - also collects Picasso ceramics, which he put on display in Leicester in 2007.
The November auction may gain additional interest from those who wish to own something the much-loved director had collected.