It looks like the flat she referred to still exists, Addison Park Mansions in Hammersmith. So we can make quite good comparison presuming one is rented out still. Though I wouldn't be suprised if they've been parted out into smaller flats, or rented as shared.

Funnily enough I'm sat in my flat about 10 minutes walk away. My building appears to have been built sometime in the late 1800s, and is somewhat falling apart. So the value for money might be even less now.