Bridget Jones's Diary...most of Sophie Kinsella's books, esp. "Twenties Girl"

Anything by Una-Mary Parker. Chris Manby writes good chick-lit, as does Jill Mansell.

White Teeth - Zadie Smith, though I've not read it, but supposed to be good!

I enjoyed Hearts and Minds by Amanda Craig.

Depends on which era, there are so many: The Crimson Petal & The White by Michel Faber (Victorian); Oliver Twist by Charles Dickens (Victorian); Tale of Two Cities, Dickens (French Revolution); Fingersmith (Victorian) and the Night Watch (WWII) by Sarah Waters; One Day by David Nicholls (1990s).

Yes - One Day is brilliant!

Barbara Vine's The Blood Doctor is exquisite... it's a mysery of sorts but also touches on topics such as the current process to reform the House of Lords. (Vine is a pen name for mystery writer Ruth Rendell.)

The classic Thackery novel Vanity Fair has terrific London scenes.

A children's book about London that I adore is Rumer Goddens' The Doll's House from 1947. Lovely story. And of course there is the classic 101 Dalmatians.

Soulless by Gail Carriger and definitely The Crimson Petal and the White. Both of those are Victorian style (although written recently). I LOVED Brick Lane by Monica Ali (which is set 90s-2000s) as well. Is there a time period your looking for?