The biscuit Factory in Bermondsey opened in 1866 was the first ever mass producer of biscuits. It was also the birthplace of the Garibaldi (1861), the mighty Bourbon (1910) and in the 30s the controversial Twiglet.
During the 70s it produced 31 million tonnes of biscuits a year! The factory closed in the late 80s, but has recently seen a revamp by AHMM Architects and is now used for exhibition, studio and office space. There's a really great cafe there with lots of celeb snaps with the manager on the walls. (I think there is a recording studio next door.) I was sitting by some american woman I recognised off the telly.
Anway, if you want to read a mouth watering Choco Leibniz biscuit review, The rather excellent Katy Scott has written one here.