Wales train crash: leaf fall and digital signalling are likely areas of inquiry

Whatever the cause is found to be, a third collision in four years is another blemish on UK's strong safety record

The fatal collision of two trains between Talerddig and Llanbrynmair in rural Wales on Monday evening is, in many respects, unique in Britain's recent rail experience: no head-on crash had been recorded this century, and only one passenger had died in a UK crash since 2007.

Inspectors from the Rail Accident Investigation Branch (RAIB), who arrived on the scene in Powys last night and resumed in daylight, are likely to release an early report this week.