Evans was born in Nottingham, England on 28 March 1928. His father George Frederick Evans was a master carpenter and his mother (née Gladys Martha Taylor) was a dressmaker. He was educated at Huntingdon Street Junior School and then won a scholarship to Nottingham High School. In 1946 he entered Oxford with a scholarship to Lincoln College where his tutor was Rex Richards (later Sir Rex Richards FRS). He won the university Gibbs Prize in Chemistry in 1949, and in that year started DPhil work with Richards on calorimetry and the magnetic properties of clathrates containing nitric oxide or oxygen; nine papers resulted from this work. He was an ICI Research Fellow from 1952-5. In 1953-4 he became a postdoctoral research associate at the University of Chicago with Robert S. Mulliken working on the electronic spectra of halogens in organic solvents, producing four papers under his own name.