“I have a call on it every single day,” says Andy Byford, Transport for London’s Commissioner. “We are micromanaging this project to the finish line.”

The tests will need to be passed before the line is finally opened, he says. “If things go well then we’ll be able to declare an official opening date”.

“I said categorically that we will open in the first half of 2022, and I’m happy to reiterate that I’m very confident,” adds Byford. “But I also want this to be reliable. No-one will thank us if we have a grand opening, and then the services are unreliable.”

Reliability is not his only concern. Executives are keenly aware that any further pushback will bring budget overruns that TfL, London’s transport authority, cannot afford. 

TfL is managing a funding gap of as much as £6.6bn, which it will have to partly plug by running already ageing trains into the 2040s and cutting bus routes. Its financial difficulties have put Crossrail 2, a planned north-south version, on hold, together with a proposed extension of the Bakerloo line.

This could partly be attributed to the rising costs of the original version. Originally proposed in 1989 under then-prime minister Margaret Thatcher, plans were approved in 2008 under Gordon Brown, before being handed a budget of £14.8bn in 2010.

Its budget has now reached £18.8bn, which could also be overshot again by up to £218m.

And while there are hopes passengers will pay back some of the costs, Crossrail is set to get going amid uncertainty about whether commuter numbers will return pre-Covid levels.

While coronavirus has a “catastrophic” effect on customer numbers, TfL’s Byford argues that they are bouncing back. On Sunday, tube passenger traffic was at 75pc of comparable 2019 levels and at 81pc for buses. 

“[Crossrail] is going to be invaluable in this country’s recovery in an increasingly competitive world,” he adds, defending the value for money the rail link will provide.

But with more people working just a few days in the office, he cannot say if the new line will simply pick off custom from the rest of the network.

“I don’t have a crystal ball any more than anyone else does,” he concedes. Connecting areas with little in the way of rail access with the city, however, as well as easy access to the UK’s biggest airport, is also likely to boost tourism.

West Ealing’s Sinha is not concerned with a drop in commuting since he predicts that people will still want to head into the city.

“I think there will always be a demand for people having to commute into London for at least two or three days of the week, and I still think that will play a major factor in property prices,” he said. 

Once the line opens and travel times drop, Sinha believes a Crossrail station will have even more of an effect on demand for nearby housing.

But for all the talk of benefiting London, the lavish planned expenditure has put the noses of leaders outside the capital out of joint as rail upgrades there have been scrapped or pared back.

Manchester Mayor Andy Burnham, for instance, has proposed a “Crossrail for Manchester” aiding transport through the city.

But TfL’s Byford insists that London’s gains can be national.

“TfL can play an absolute part in levelling up because we spend 55 pence of every pound around the country,” he says. “We buy buses in Ballymena and Falkirk and new trains for the Piccadilly line in Goole in East Yorkshire.”

“If someone said to me, if you could turn the clock back and not build the Elizabeth line, I would strongly advocate against that. It will stand the test of time.”