Ben Nicholson’s Still Life with Mug Decorated with Stag, estimated at £80,000-120,000Credit:Sotheby’s Mr Attenborough added his mother had worked as an “accomplice” to accumulate more art works than they could fit in the house, joking they were “terrible hoarders” who “absolutely loved” to collect things which would enrich the lives of those around them.The couple previously held their own sale at Sotheby’s in 2009, making £4.5m from works of art.Lord Attenborough died in 2014, shortly before his 91st birthday. His wife Sheila died in the same year, after 69 years of marriage, three children and six grandchildren. They are survived by their son Michael and daughter Charlotte, an actress.Mr Attenborough said he and his family had already been given treasured pieces of art, personal mementos and Lord Attenborough’s many awards, with numerous works of art now ready to give pleasure to others.“Simply there’s no further places to hang them, to be honest,” he said. “Some of them are well beyond our budget in terms of insurance; it is very expensive to insure paintings of that sort of value. Star items include a Henry Moore drawing of a Second World War bomb shelter, now estimated at up to £250,000. Similar pictures are held by the Imperial War Museum.A Ben Nicholson painting, Still Life with Mug Decorated with Stag, will sell for up to £120,000, while William Scott’s Flowers on a Blue Cloth is offered for £35,000.Lord Attenborough, his son said, had had “unapologetic love of all things British”, seeking out 20th century paintings “he knew would give him infinite pleasure”. Lord Attenborough and his brother, Sir David, photographed in 2006Credit:Getty Henry Moore’s Shelter Drawing, estimated at £150,000-250,000Credit:Sotheby’s “When some of the paintings were leaving the house [in the 2009 auction], he couldn’t bear seeing them go and they were very quickly replaced with something from a store room.“There were never any gaps. He never ever bought a painting as an investment. He fell in love with paintings and loved collecting. It was just passion of his.”Sotheby’s said the collection had been assembled with “immense passion and a very distinctive eye”.The sale will take place at Sotheby’s on the 22nd and 23rd of November. Henry Moore’s Seated Woman: One Arm, estimated at £40,000-60,000Credit:Sotheby’s Richard and Sheila Attenborough photographed together in 1991 When a much-loved parent dies, many will be faced with the dilemma of what to do with decades’-worth of accumulated treasures.Few will confront such an abundance as the children of Lord and Lady Attenborough, who are to sell an unrivalled collection of modern British paintings after finding they simply did not have the room or means to keep them.Michael Attenborough, their director son, said he would be sad to part with the 37 works of art, from Henry Moore to Dame Elisabeth Frink, but that they were too valuable to keep, needing high insurance costs to keep them out on display. “Bless them, they had a huge collection in a very huge house. I can’t pretend other than it’s kind of painful to lose them [the art works]. “I would love to think they could go to somewhere a lot of people could enjoy them.”Speaking of his father’s passion for collecting , he said: “Sometimes his love of art led him beyond the space on the walls. Craigie Aitchinson’s Tree, estimated at £10,000- £15,000Credit:Sotheby’s His parents, he said, collected through a passion for art, and would want them to be on the walls for others to enjoy.The sale, at Sotheby’s, will include works collected by Lord and Lady Attenborough from the days of their early marriage, bought before they could afford carpets or curtains for their Richmond family home.Picked up at auctions, from galleries and occasionally as gifts from the artists themselves, they are now estimated to sell for around £1million, with a further £1.5m from a separate sale of Picasso ceramics. Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings.