London Mayor Sadiq Khan joins a driver in the cab of a Crossrail train as it travels through one of the new tunnels. Tap above to watch video report by Simon Harris.
Crossrail is coming and - whisper it quietly - it might arrive sooner than expected.
ITV News was invited to see progress on the £18.7bn railway by taking a journey into the future - a ride on a train below the capital's streets.
London invented the underground railway more than 150 years ago but Crossrail ushers in a new era of subterranean travel.
Forget the cramped conditions on traditional Tube trains, the narrow platforms of the Northern line and the rattling, clapped-out carriages on the Bakerloo.
The nine-coach Crossrail trains are sleek, shiny and above all quiet, gliding effortlessly along new tracks without a hint of screeching wheels.
The stations are cavernous and cathedral-like. Deep beneath Brunel's magnificent Paddington, the new station is a worthy addition to its illustrious predecessor.
I was among the first journalists allowed to travel through Crossrail's central tunnel along with a party of VIPs including London mayor Sadiq Khan and Transport for London commissioner Andy Byford.
We were welcomed aboard by an automated announcement declaring: 'This is a TfL rail service to Abbey Wood via Canary Wharf.'
Our journey from Paddington to Liverpool Street lasted just 12 minutes, less than half the time it can take on the Hammersmith & City Line.
A little way into our journey we were reminded of Crossrail's troubled past as the train stopped at Bond Street. It remains the only unfinished station and will not be ready when the line opens.
Crossrail will eventually be named the Elizabeth Line in honour of the Queen who was due to perform the opening ceremony on December 9th 2018.
But the construction project was in trouble, years behind schedule and over-budget.
After the opening date was missed, a clear out of bosses followed and a new team set about rescuing London's flagship transport scheme.
So when will Londoners finally get to travel on their new railway?
Publicly, Byford is committed to opening Crossrail in the first half of 2022 - so before June 30th.
But he told me he was pushing his team to get 'as early a date as we possibly can'.
"I don't have a precise date yet, I want to be certain the service is completely reliable," Andy Byford told ITV News London.
I understand TfL would like to invite the Queen to officially open the line before her Jubilee celebrations at the beginning of June.
Between now and then, empty trains will continue running up and down the tunnels as engineers iron out software bugs and test safety systems.
Byford said nothing would be left to chance and the opening would be flawless
He added: 'Londoners won't thank me if having waited all this time and having spent all that money, the service is less than perfect'.