Mr. Lionel Staples Gunaratne started his teaching career in 1964 as a pupil teacher. In the same year he entered the Peradeniya university and completed Bachelor of Education degree. In 1969 joined St. Thomas's college Mount Lavinia teaching staff. Having completed a master’s degree in 1973, joined Ministry of Education.

In the year 1978 Mr. Lionel Staples Gunaratne joined the teaching staff of Royal College. He also served as the master in charge of hockey and as the acting secretary of Sri Lanka schools lawn Tennis Association. Late Mr. L.D.H. Peiris was the president of the same.

Mr. Lionel Staples Gunaratne left Royal in 1985 to join the Department of Examinations as the Assistant Commissioner of Examinations and later promoted as the Deputy Director of Education

In 1990 he migrated to Australia and served in education roles at Seven Hills High School, Hurstville Boys High School and at James Meehan High School.