Hartley spent a year at the University of Chicago, and another at MIT before being appointed as a lecturer at the newly established University of Warwick in 1966, and was promoted to reader in 1973.
Hartley spent time studying at the University of Chicago for a year and then at MIT for another year. He was later hired as a lecturer at the University of Warwick in 1966 and was promoted to a more senior position as a reader in 1973.