Holmes lived in Victorian England, a much different place and time than England today. Many of Holmes' fans aren't even English, and therefore have some trouble with the history, and particularly currency. I've compiled a list of links that should be helpful, and if you need anything else, I'll be happy to look it up for you.
British Currency Before 1971
Wages, Cost of Living, Contemporary Equivalents to Victorian Money
Wages and the Cost of Living in the Victorian Era
Life and Times of Queen Victoria
History of the Monarchy: Victoria's Reign
British Imperial History
The Crimean War
Parliament: What is it, and how does it work?
Victorian London
Railway map of 1899 London
Sherlockian.net, an overall good resource
Holmes, Sweet Holmes - OMG THERE'S A MOVIE
