Transport for London was unable to confirm an exact date for when the first Class 345 Aventra electric multiple unit for Crossrail would enter traffic.

The £1 billion train fleet is being built by Bombardier at Derby Litchurch Lane, with three trains so far delivered to Ilford for testing and training. TfL documents from March confirmed that the first train due to enter traffic was meant to be 345005 on May 23 (RAIL 826). It was to be used on the Shenfield to London Liverpool Street metros, with 11 in traffic by September.

A TfL spokesman gave no reason for the delay, telling RAIL: “They are still testing. There is no firm idea .”

TfL has 66 nine-car Class 345s on order. The first 15 will be delivered as seven-car trains initially, before being extended to nine-car sets. There is consideration for extending the deal to 70 trains.