He had a steady start to his career on tour before being struck down with ME (also known as Chronic Fatigue Syndrome) in the early 1990s.

[4][2] He returned to form in 1993, to claim his first tour victory in the Turespana Masters Open de Andalucia.

The undoubted highlight of his career came in 2001 when he became the oldest winner in the history of the Volvo PGA Championship (although Miguel Ángel Jiménez would later beat that record).

[5] He finished that season a career best 26th place on the European Tour Order of Merit.

European Senior Tour playoff record (1–0) Note: Oldcorn never played in the Masters Tournament nor the U.S. Open.