Mr Hicks, once described as a wet of "oceanic proportions", is MP for South East Cornwall and was first elected to Parliament in 1970.
He said: "Both Parliament and the Conservative Party have altered as you would expect over my time at Westminster. Unfortunately, in my judgement, neither has necessarily changed for the better."
Mr Hicks, 57, said: "Had anyone suggested that when I left university I would spend three-quarters of my working life in the Mother of Parliaments, quite frankly I would not have believed them."
He represented Bodmin from 1970 to 1983 with a brief break between the February and October elections in 1974. The seat became South East Cornwall in 1983.
His "liberal" stance on many issues probably kept him on the back benches for most of his political career. He was an assistant whip in 1973-74.Reuse content