This Watch House was built in 1761, to keep guard over the Church of the Holy Sepulchre's graveyard, which was then much larger and extended across the road. A night watchman was employed here to stop recently buried corpses from being stolen by 'ressurection men' (body snatchers).
In the late 18th Century, the field of medical science was growing. In the past, the corpses of executed murderers had been used for teaching and medical dissection.
Now, however, as there were more surgeons and students than before, there were, not enough of these corpses available. As a result, gangs of 'ressurrection man' started to dig up bodies, which had just been burried, and sell them to hospitals. As well as being gruesome, body snatching was not easy - the most usual technique was to dig down six feet, late at night, making a single hole in the lid of the coffin and pulling the body out with a rope. The body snatchers often knew where to find the grave they wanted to plunder, because they had actually attended the funeral of the deceased.
Bodies stolen at this graveyard would usually be taken to an inn on the opposite side of the road, where the landloard would tie the name of a doctor or student, who had paid for the body, on the body's toe. Then the doctor, from a nearby hospital, such as St Bartholomew's Hospital, would visit the pub, and pay the landloard for the body. The students who bought the bodies used them to practice surgical techniques. It will come as no surprise then, to find that the Physiology Department of St Batholomew's Hospital is directly opposite the graveyard. The ressurrection men could make a good profit and body snatching became a problem. The practice only stopped when some of the body snatchers (such as Bishop and Williams) turned to murder.