The former chairman of Crossrail is set to be challenged whether the Mayor of London knew about the Elizabeth Line delay days or months before it was announced.

Terry Morgan, the former chairman of Crossrail – the company managing the Elizabeth Line extension – will face questions from the London Assembly transport committee on Wednesday, January 9.

On December 21, 2018 the assembly scheduled an emergency meeting with Mayor of London Sadiq Khan to clarify when he found out the Elizabeth Line extension would not be opening on December 9, 2018, as planned.

The Elizabeth Line will run between Liverpool Street and Shenfield but on August 31 it was announced it was not expected to open until Autumn 2019 – although a final date has not been confirmed.

Mr Khan always insisted he only discovered the project was delayed two days before the announcement from Crossrail in August.

But earlier in December Mr Morgan told Radio 4 he first informed Mr Khan there would be a delay on July 26, 2018.

Commenting on Mr Morgan’s accusations at the meeting on December 21, 2018 Mr Khan said: “Either Terry Morgan is misremembering this or deciding not to remember.

“I apologise to those who want a smoking gun, there is not smoking gun.”

But the chairman of the transport committee, Caroline Pidgeon, vowed to find out whether Mr Khan knew about the delay of the Elizabeth Line extension earlier then he said.

Ms Pidgeon said: “It is very frustrating that despite a long meeting, with summonsed documents, the Mayor and the TfL commissioner speaking at length, we’re still far from understanding who knew what and when.

“Someone between these two parties is not giving a full account and we will stop at nothing to get to the bottom of this.”

The London assembly will also meet Transport for London (TfL) bosses on Monday January 7 to discuss the transport body’s budget.

The meeting was originally scheduled for December 17, 2018 but was postponed because TfL handed in its business plan 11 days late – the plan arrived just four days before the original meeting.

The Assembly said they “simply had no option” but to cancel the meeting.

Commenting on the delay a TfL spokesperson said: “It wasn’t possible to publish a Business Plan until a deal had been done with Government on the financing of the Crossrail project and we published the plan one day after that deal was agreed.”