Mr Dennis, an extrovert publisher, poet, tree planter and entrepreneur had a vision to create a 30,000 acre forest in the heart of England and all the proceeds from the auction will go to the charity Heart of England Forest.
Mr Dennis died at his home in June last year at the age of 67, after a two year battle with throat cancer.
Jeremy Lamond, fine art director at Halls in Shrewsbury, who are conducting the 2,300-lot auction jointly with Bigwood Fine Art Auctioneers of Stratford, said: “Estate auctions of this type are few and far between and it’s particularly fitting that it’s being held on Felix’s estate.
“It’s a hugely exciting and eclectic sale with literally something for everyone.
“There is a delightful mix of antique and modern with 17th and 18th century oak and walnut furniture alongside contemporary designer furniture and objects.”
Christopher Ironmonger, director of Bigwood Fine Art Auctioneers, a business colleague of Dennis for over 12 years, added: “The auction will provide an opportunity for the world to appreciate the magnitude of Felix’s collection.”
Some of the more unusual items include ejector seats from a Canberra bomber and a Vampire jet fighter, valued upwards of £500 each, and a gypsy caravan bearing the name Dennis, which is seeking a new owner for in excess of £800.
Potential stars lots include a French silver racing trophy at up to £50,000, a mid-19th century carved British Royal coat of arms at up to £8,000, a Kashmir silk carpet at up to £6,000, four driftwood sculptures of curlews by Guy Taplin (born 1939) at up to £3,000 each and an exhibition piece Moorcroft vase at upwards of £2,000.