On Jul 6, 12:44 pm, "Jack Taylor" wrote:

Could it simply be down to a bit of over-zealous fault reporting?

No, the reliability figures are based on miles per casualty, a
casualty being defined as a fault which causes a delay of five or more
minutes. Air-con faults do not normally result in a train being
delayed. Faults with engines, doors, couplers, TPWS, etc do, and when
a train sits down on the line with one of those, there's no question
of under-reporting it.