GLENGARRIFF native Darragh McElhinney, running in the UCD colours, is the eighth Corkman to break the four-minute mile.
Running in the final race on a programme of mile races at Wimbledon he quickly established himself in the leading group and then settled into fourth place, a position he maintained for three laps.
Going into the last lap, it was Australian Matthew Ramsden, a 3:51 miler, who lead the race and he went on to win in 3:55.78. Behind him, McElhinney overcame English runner Jack Rowe with 100m to go to finish second in 3:58.20.
His previous best was 4:04.57 indoors last year.
This result highlights once again how badly he was let down by Athletics Ireland team management at the recent European U23 Championships when he was forced to run by himself in the 5,000m B race depriving him of a medal.
McElhinney holds the Irish junior 3,000m and 5,000m records outdoors and the indoor record for 5,000m. He is also the holder of a European junior bronze medal over 5,000m.