Exceedingly quick. It is shown as 5.05k so quicker than Steve Cram ever ran 5k in his life and faster than anyone ran 5k in UK last year ...and in a pair of baggy shorts and an ill fitting waterproof jacket! Naturally among the comments there are many reservations about faulty recording, mainly downhill, and insufficient leg speed on accompanying video clip. etc. Others suggesting its quite normal and that plenty of people run that fast when trying to get through Gipton.
Going by his Strava activity (
https://www.strava.com/activities/4748319774), the distances are out by 15% or so
(5.8 km rather than 5.05 km for the 5 laps of the triangle round St Nicholas school, and 7.7 km rather than 6.6 for the whole track).
15% on the time gives a rather less impressive 15:25
It comes down to whether the claim is based on the track, or whether he timed the 5 laps with a stopwatch, as being a known distance.