Could this be London's property hotspot in 2040?

They are two vast sites on the banks of the Thames in east London and you probably haven't heard about them.

But the chances are you might soon.

These are huge development areas called Thamesmead Waterfront and Beckton Riverside. Both are brownfield sites and are earmarked for huge housing developments of thousands of homes, shops and amenities.

The problem is these are among the few areas in London without a rail or Tube link and that is stalling development.

What the developers and the mayor want is a commitment from government to an extension of the Dockland Light Railway (DLR).

Could that happen in the chancellor's Spending Review?

Ed Mayes is the executive director for development at Lendlease, which will develop the Thamesmead site.

"Our priority for Thamesmead in particular is the DLR extension. We have already got commitment from the mayor and there is commitment from Tfl for the initial stage of funding," he told BBC London.

"But what we really need is a government commitment that subject to that initial stage of work they are willing to help fund the actual delivery of the DLR."

He says a transport link is crucial.

"It's been proven across London that transport infrastructure unlocks delivery of homes; that's happened with the Jubilee line and the Elizabeth line, it will continue to happen.

"This is an area of London that has amazing potential: there could be 15,000 homes at Thamesmead Waterfront, another 15,000 on the north of the river in Beckton - all unlocked by that extension.

"In addition, there's future potential if it was extended in the future. That will unlock homes, much-needed affordable homes for London, but also the jobs and enterprise that comes with that."

It is perhaps no surprise that London Mayor Sir Sadiq Khan is framing what transport infrastructure he wants in terms of housing.

Of course, creating housing through transport links is not a new idea in the capital. Just one example is the Metropolitan line creating the suburbs in the north west of London dubbed "Metroland".

Today, the main projects on the City Hall wish list are the DLR extension to Beckton Riverside and Thamesmead Waterfront, the Bakerloo extension and the West London Orbital.

All of them link areas where thousands of homes could be built.

These links do not come cheap though and are beyond the realms of Tfl's budget and so funding would have to come from government.

A DLR link to Thamesmead would cost about £1.5bn and involve a tunnel under the Thames.

City Hall said in a statement: "The mayor wants to work in partnership with government to support the national growth agenda. With the right investment and devolution of powers, there is a huge opportunity to unlock growth; create new jobs; attract international investment; and ensure London contributes more to the national economy and the Exchequer's finances."

Just down the road from Thamesmead is Abbey Wood. It got an Elizabeth line station three years ago. Once known as the cheapest postcode in London, the area is changing.

John Lewis is executive director for sustainable places at Peabody, which developed the Southmere Lake site in Abbey Wood.

"I think in any part of London that's changing, if there hasn't been an established market or people don't know the area, you need to give some confidence, you need a reason to come and visit," he said.

"I think with the arrival of the Elizabeth line, people really understood that it was a new area opening up to a lot of Londoners so we saw people from east London coming here to visit for the first time and recognise all the open areas and green space.

"People started to recognise this was somewhere they wanted to view and ultimately move to."

There have been objections to the Southmere Lake redevelopment, though, with opponents saying some of the homes demolished to make way for it should instead have been refurbished.

As regards Thamesmead Waterfront, a project he is also involved in, Mr Lewis says transport infrastructure is critical.

"I think what's really exciting about the Waterfront is 100 hectares of land that's hardly been developed at all. In London terms that's unheard of.

"You have two kilometres of the waterfront of the Thames and we have got the capacity to get 15,000 homes built and a million square feet of other uses.

"It would be a new neighbourhood for London, but the critical thing we need to make that happen is the arrival of excellent public transport - which is bringing the DLR over to Thamesmead."

The government's target is to build 1.5 million new homes by 2029.

And if London can't deliver a large number of new homes, there is little chance the government will hit that number.

To do that, it will mean transport infrastructure being funded to reach the undeveloped sites in Thamesmead and Beckton.