He eventually overcame this setback to make his league debut on 18 April 1967 in front of a 54,921 crowd at Old Trafford as relegation-threatened Saints went down 3–0 to Manchester United.

He was slightly built for a defender and "although quick and diligent, he struggled to carve a permanent niche in Southampton's notoriously robust rearguard".

Having given away Derby's 88th-minute goal after a poor back-pass, Byrne quickly turned from villain to hero as he slotted in a bobbling ball in the 90th minute in a dramatic climax to the season.

In August 1974 he moved to Hereford United to join former Saints' colleague Terry Paine for three seasons before finishing his career with Newport County.

Amazingly his Irish international debut in October 1969 in Dublin against Denmark was the first time he had kicked a ball in his native land because he had emigrated to London with his parents at the age of 12 and, until then, had played only hurling.