Before the modernist period London had distinctive tenement housing styles.
The Peabody Estates were one of the first social housing movements in the West. Distinctive streetwalls, yellow brick, minimal decoration, lots of small windows, and stripes. Some are now luxury conversions, others are still social housing - despite the good intentions, embarrassingly they bear striking similarities to Victorian prisons.
https://i1.wp.com/londontraveller.org
If not for the sloped rooves, many would look almost modernist.
www.erichall.eu
Then there are these art deco 'gems'. To this day they are still a sign of poverty and a dank home where sunlight fears to tread. Defined by brown brick, setback fronts, and horrible stairwells. And worst, the narrow walkways where people constantly squeeze past every window, so even more netting's put up and even less lighting gets through.
www.peabody.org.uk
Although historic, ugly AF. They can of course be luxed up by developers and trade hands for $1.3 million a pop, provided they're in the right area. The vast majority aren't, and clog up the East End and south of the river.
Large areas of West London also have street after street of art deco mansion blocks, that were de rigeur for the glitterati back in the day. Once again, a bit ugly imo - depressingly brown brick (the WORST colour for the British weather, yet almost ubiquitous for centuries), and not that many art deco features really. I'd call this the fine line between pared down art deco and modernism, and a relatively unique format to London.