Harnam Singh Grewal was born in Hong Kong. He studied at Ballowal Village Primary School. district Ludhiana, Punjab from 1943 - 47.
He studied at Sir Ellis Kadoorie School, Hong Kong from 1947 - 51; Kings College, Hong Kong 1951 - 56; University of Hong Kong from 1956 - 60.
He obtained BA (Hons), Dip. Ed. and MA at University of Cambridge in 1960 - 62.
He was a teacher from 1962 - 64 and an Adminstrative Officer in the Hong Kong Government from 1964 to 1990.
He played for Nav Barat Club from 1953 - 90; Royal Hong Kong Hockey Club from 1973 - 90 and has been a member of Oak Bay Lawn Bowling Club since 2001.
Harnam represented Hong Kong at the 4th Asian Games in Jakarta in 1962.
He represented Hong Kong at the Tokyo 1964 Olympic Games.
He represented Hong Kong at the 5th Asian Games in Bangkok in 1966 and the Far Eastern Regional tournament in Hong Kong in 1969.
Harnam was the President of Hong Kong Hockey Association from 1968 - 72
He is the Vice-Patron of Hong Kong Hockey Association.