Missing Darwin notebooks returned to Cambridge Uni, with 'Happy Easter' tag

A view of the 'Tree of Life Sketch' in one of naturalist Darwin's notebooks which have recently been returned after going missing in 2001, in Cambridge, England. Two of Darwin’s notebooks that were reported stolen from Cambridge University's library have been returned, two decades after they disappeared. Photo: AP

Two of Charles Darwin's notebooks containing his pioneering ideas on evolution and his famous "Tree of Life" sketch have been returned anonymously after going missing for 21 years, Cambridge University Library said on Tuesday.

The prized documents were left on the floor in a public area of the British university's library in a pink gift bag, with a typed note wishing a Happy Easter to the librarian.