Indeed, this seemed to indicate that the rent has increased disproportionately. The article mentions that the rent would cost $500 in today's dollars. That's very cheap for 4 bedroom apartment everywhere in western world, especially in London.
Maybe that car was really rubbish by today's standards and technology-wise therefore it is expected that now the real costs have come down. But with apartments I don't think there is that much of an improvement that justify average increase from $500 to $5000.
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.
What's more interesting, is that somehow very few new nice areas (towns, cities) have been built. Take almost any area in London with anything built after the 1950s, and in many cases the new buildings make the area far worse, not better. Kensington is still the size it was, and there are hardly any new Kensingtons available - and a lot less affordable for an average professional.
London is wealthy enough for there to be no 'bad areas'.
Maybe that car was really rubbish by today's standards and technology-wise therefore it is expected that now the real costs have come down. But with apartments I don't think there is that much of an improvement that justify average increase from $500 to $5000.