Keen's Mustard has a history extending back to the 18th century. The first mustard factory in London was opened by Messrs Keen & Sons at Garlick Hill in 1742, and in the 1890s the chimes of the Royal Exchange, set to the well known song 'The Roast Beef of Old England', could be heard, during a lull in the traffic, at Keen's factory. Part of the factory was sealed off for manufacture of washing blue, because everything, including the workers, bore a shade of blue. Mustard tins too were made, and there was a penny tin packing room.