This clock is one of the most important examples of glazed mantel clocks commonly known as four glass clocks.

The individual who ordered this clock must have specified that no refinement should be spared. The dial, the movement, the case and the travelling box are all of the very best quality whilst its large and handsome proportions leave no doubt in the mind that it would have required a very deep pocket indeed to have bought this clock

The travelling box has always been an interesting feature of English carriage clocks. The present clock has its original plush velvet lining and the sensible provision for the large chronometer winding key. The locks comprise two large gilded latches and a Bramah lock. Joseph Bramah was a Yorkshireman who invented and patented a unique type of lock in 1784. It was apparently partly based on the sliding principle of an ancient Egyptian lock; it was extremely complicated and very expensive. At the time however burglaries were a cause of great concern and because the lock was considered unpickable Bramah became a household name. The unfortunate consequence was that if the key were lost there was no alternative other then to break it open, often causing considerable damage not only to the lock but also to the the piece of furniture.

During the 1851 Great Exhibition an American locksmith by the name of Hobbs claimed that he could pick Bramah's special lock that had remained inviolate in Bramah's shop window for fifty years. A committee of eleven men was quickly set up; they gave Hobbs thirty days to pick the lock and ruled that if successful he was to be paid the enormous sum of 200 guineas. Hobbs took ten days working four hours a day to pick the lock, Bramah was shattered and protested Hobbs had actually broken the lock, but the original key was then used and the lock operated perfectly, at which point Bramah had to concede.