Jones grew up in Ebbw Vale, Wales and ran his first race at the age of 15 as a member of the Air Training Corps.

After receiving an invitation to the 1983 Chicago Marathon Jones began training for that distance; he previously had specialized in the 5,000 and 10,000 m,[1] and on 6 August 1984, he ran the 1984 Olympic 10,000 m event.

[2] On 21 October 1984, a year after he had dropped out of the Chicago Marathon because of an injury, Jones won the event—his first completed marathon—with a time of 2:08:05, breaking the world record of Australian Robert de Castella by 13 seconds.

He won the 1985 London Marathon in 2:08:16 despite stopping to go to the toilet during the event; Jones later said, "I didn't even train for [the race]", instead continuing to coach himself.

In the race, Jones was leading from the start with 30-metre margins up until the last 400 metres, at which point the commentary (from David Coleman) noted "But they are closing.

This race was an invitational held in Memorial Van Damme Stadium, Brussels, 1983, and hence not recognised in official competitive records.