Duffy began his professional career with Dundee United at the age of 17 after passing a first team trial whilst on holiday in 1985. Soon afterwards, however, he returned to South Africa due to homesickness. In South Africa he again played for Shamrocks.
Duffy began his professional football career with Dundee United at the age of 17 after an impressive trial during a summer holiday in 1985. However, he soon returned to South Africa due to feelings of homesickness and resumed playing for Shamrocks.