The Transport for London Commissioner claims Crossrail 2 is needed because London's population is growing by "a tube train a week".
Peter Hendy joined Mayor Boris Johnson at the launch of a public consultation where the price tag for the project remained a mystery. Simon Harris reports.
More top news
The plaque at number 16 Cowley Street in Westminster marks the brown brick Georgian townhouse where Sir John lived for 31 years.
A man reportedly armed with several knives has been arrested in Whitehall on suspicion of planning a terror attack, police have said.
Metropolitan Police officer, Tom Harrison, has been crawling the course since the race began on Sunday morning.