The Regency Underworld by Donald A. Low. A look at the lowlifes, gamblers and grifters of Jane Austen's time.
Harriette Wilson's Memoirs: The Greatest Courtesan of Her Age edited by Lesley Blanc- This is a Regency England era tell all book in which the narrator doesn't hold back. The biggest names of the Regency from Beau Brummel to the Duke of Wellington make appearances in this lady's memoirs. Written in the style of the era, it isn't the breeziest of reads and the author is a bit scattered, but she's fun and frank and well worth the time.
Victorian London: The Tale of A City 1840-1870 by Liza Picard - Everything you wanted to know about Victorian London from medicine to museums. Be glad you weren't sick back then.
Upstairs and Downstairs: The Illustrated Guide to the Real World of Downton Abbey by Sarah Warwick. If you love Downton Abbey and want to learn more about the less than glamorous life of an Edwardian servant, this book is for you. It's light reading with lots of vintage photos. It makes me glad I wasn't a working woman back then.