HMS XE9 (Lt S H Kempster) was one of several midget submarines which was programmed to give displays of diving and re-surfacing for visitors to the Navy Days in the dockyard, 8 – 10 April 1950.  On the day before, Good Friday, the submarine was lying alongside HMS BIRMINGHAM at Fountain Lake Jetty in Portsmouth, charging the batteries ready for the next day’s displays, when Lt Kempster heard a loud explosion.  Hurrying back onboard he found LEM Lloyd, who was alone onboard at the time of the blast, badly burned in the cramped battery space.  He was rushed to hospital but died later that day.

Extractor fans used during the charging process were found to have been working perfectly and the build-up of Hydrogen gas which caused the explosion was never satisfactorily explained.