A transport union has claimed it is only by 'pure chance' that the threat of a train derailing was avoided after a signal collapsed just yards from a well-used track.

The RMT has released this picture of the semaphore signal, which came down at Cantley on the Norwich to Lowestoft line and landed on a grass verge next to the busy line.

Union members said they had flagged the rusted metal post to managers and warned of it being an issue. But they claim they were told that signalling was to be replaced with a new centralised system, so repairs and replacements were not required.

A spokesman for National Rail said the working signal was brought down by high winds at the end of March and all similar signals would now be investigated.

Mick Cash, RMT general secretary, said: 'It is pure chance that the signal didn't fall across the track threatening life and limb. Safety on our railways should never be left to luck.

'RMT will be raising this issue at senior level with Network Rail and we expect them to listen and to take the appropriate action.'

The Network Rail spokesman said: 'We recognise this was a serious incident and will be carrying out detailed inspections of all signals of this type to ensure they are structurally sound.'