An underground extension beneath the garden lawn
The Ilford home of school teacher Marian Myers and her family appears little different to the other chalet-style homes on this tree-lined road.
There are signs of renovation - extensions in the roof line and one to the rear - but nothing unusual.
Even the back garden looks like any other, until you notice the square glass windows in the ground - one in the decking, the other beneath a children's slide.
In fact, underneath almost the entire garden is a large underground extension, measuring some four by 10 metres.
The route to the below-garden extension is through a door in the kitchen which leads down to a play room populated by prams and glitter balls. It is very light - and large.
"It's a bit of subterranean living in urban Ilford," Ms Myers says as we stare up to the garden and sky above us.
"It's soundproof as well, which is great when you've got five or six children in here. We've lost no garden at all upstairs and gained so much space downstairs. It's brilliant."
So soundproof, indeed, that when the children want to communicate from the garden by knocking on the windows, she can't hear anything.
"It's a perfect solution," she laughs.
The room is lit by two bullet-proof roof lights and features a ventilation system and a pump to remove waste from an adjoining shower room.
Existing planning laws would have made such a large extension above ground impossible.
The extension is the work of Stuart Moss of Underground Living, a builder and planning consultant. It's his first such project and came in at £120,000.
He says the idea came to him when he looked at the need for space in his own house.
"We were running out of space at home - children growing up, getting bigger and we were just thinking 'What's the next stage if they can't afford to move out?'" he told BBC News.
"That's where the crazy idea came from - can we live underground and build underground?"
Ms Myers' home is by no means the first house in the UK to go underground. Several subterranean "eco-houses" have been built, using earth to insulate the home - not least the former Manchester United footballer Gary Neville's "flower house".
There has been a drive too within more salubrious postcodes of the country to excavate basements to create more space. This has included applications - some successful, others not - to go under the garden.
The planning application for the Ilford extension was considered by the planning team at the local Redbridge council offices.
"It's not the sort of run-of-the-mill mill application that you would normally expect to receive," planning officer Alan Romain told the BBC.
"If we had that depth of extension which was on the garden itself, then it would be unlikely to get planning permission.
"But the only part of the development which would be visible to a local resident were the roof lights, and members were quite happy if that was the only effect there was, then planning permission should be granted."
"It's a very innovative way of retaining garden space yet also providing additional floor space"
A radio report on the underground extension will feature on Radio 4's PM programme Thursday at 5pm