O'Brien was born in Newport, Wales. In 1958 he was a telegraph messenger, was the Welsh junior butterfy champion and record holder.[2]
He was a member of the Newport Swimming Club[3] and in September 1957 broke the Welsh junior butterfly record after recording a time of 69 sec.[4] In March 1958 at the Empire Games trials, he set another Welsh junior record, when timed at 1 min 14.5 sec for the 110 yards butterfly, in addition to winning the senior 220 yards butterfly event.[5]
He represented the Welsh team[6] at the 1958 British Empire and Commonwealth Games in Cardiff, Wales,[7] where he competed in the 220 yards butterfly event.[8]
