Before WW2, every year, "The Yard", as it was known, had a week-end open to the public. There were always many ships & submarines on display that the public were allowed to tour. I well remember going below in a sub. in one of the basins. All the way from conning tower to forward torpedo tubes, as a young lad,probably 1938, it was the 2nd highlight, The first was when an aircraft-biplane I'm sure- flew over & the observer in the back seat leaned over & dropped bags of flour onto a sloop that was firing anti aircraft guns at it from one of the basins. I think 1/2 the Medway Towns turned out- very popular!