Ian Thwaites was born in 1943 in Brighton, the youngest child of four to Guy Thwaites, a local general practitioner (GP).[3] He was educated at Eastbourne College and Gonville and Caius College, Cambridge, where he studied Natural Sciences.[4] He played cricket for Sussex Second XI and Cambridge University, and in 1964 won a Blue.[3] Following training in medicine at Cambridge and St Thomas’ Hospital, he became a doctor and worked in Africa before moving to Horsham, where he worked for over 40 years, first as a GP, and then as a private sports physician.[3] The cricketer Christopher Martin-Jenkins, in his autobiography CMJ – A Cricketing Life, describes being treated by him.[5] Thwaites was a member of Horsham Cricket Club, where he played cricket for many years, and he was a co-founder of Keep Southwater Green.[3][4]
His son, Guy, also played first-class cricket for Cambridge University.[6]
He died from prostate cancer on 30 September 2015.[3]