Crossrail engineer was 'working in excluded area when concrete fell which killed him'

In an interview with London Live today, Mr Morgan said: "A particular individual was on a work site doing a very careful job in terms of what we call spray concrete up the walls we were building, and this individual went into an area that was excluded....[he] shouldn't have been there, and we're still trying to work out why it happened."

A spokesman for the Health and Safety Executive, which is responsible for regulating workplace safety, said the investigation into Mr Tkacik's death was ongoing and would not comment further.

Workers are digging about 25 miles of tunnels underneath the capital for the new train line, which will stretch from east to west London.

Last month it was announced that follow-up project Crossrail 2, which will link Surrey to Hertfordshire via London, could be completed by 2029 - four years earlier than initially proposed.