The RAIB statement says:
The collision occurred because a set of points were misaligned and directed the passenger train away from its intended route. The misalignment was a consequence of a temporary modification to the points control system which also caused the train driver and signaller to receive indications that the points were correctly aligned.
Our investigation will examine:
- the circumstances leading to installation of the temporary control system modification
- the safety measures provided while the temporary modification was in place
- the checking and testing procedures applicable to the modification
- any relevant underlying management factors.
Bloody hell!
Eye thought the IRSE's vice like grip on signal testing was supposed to prevent this sort of thing happening?