Bennett was born in Tottenham and was educated in Enfield where his contemporaries included John Reeve.

His brother was working on an edition of Gilbert White's book when he died and it had to be completed by John.

[2] His gravestone has the inscription "He quitted London retiring from the world and its cares to end his days in the peace and quietude of his secluded country home."

On the evening of 30 June 1858, Charles Lyell and Joseph Dalton Hooker passed on to him papers by Alfred Russel Wallace and Charles Darwin, titled "On the Tendency of Species to form Varieties; and on the Perpetuation of Varieties and Species by Natural Means of Selection" respectively.

As secretary of the Linnean Society at a meeting on the following evening, 1 July, he read out the papers together with a covering note by Lyell and Hooker.