What kind of currency were they using in the Guy Ritchie "Sherlock Holmes" film?

In the movie, Robert Downey Jr's Sherlock Holmes character is constantly passing and receiving these large white pieces of paper-they have writing on them and possibly some kind of stamp, almost 8x10 in size-as currency (winnings for a boxing match and money owed to Watson which it appears he's intending on using to purchase an engagement ring). Does anyone know what this is called? Was it common currency for late 19th Century England? I'm having difficulty finding similar looking currency online.