Not sure what to post this under Very interesting blog by Martin .Stanley With his permission I am posting hoping for more information. Hornchurch & The Bouncing Bomb by ukcivilservant Can anyone help solve this mystery? This – surely unique – bomb-proof building was constructed at great expense a couple of years before the Second World War. It sits in the grounds of a house in Emerson Park, Hornchurch, then owned by a senior naval architect called Lazarus Serafim Polychroniadis. He had left Athens to make a career in England at the end of the 19th century and was particularly knowledgeable about the effect of water pressure. His daughter Dorothea worked for Winston Churchill during the war and it is believed that Churchill visited the Polychroniadis family during the war. The 5 metre square building has extremely thick concrete walls and was provided with its own heating, ventilation, and flushing lavatories. . The only external ‘window’ was a pressure-defying re-purposed submarine hatch. And the only external door was made of strongly reinforced steel, whilst its hinges, too, were made of very thick steel. A 10 ton crane stood outside, powered by non-domestic three phase electricity, which is used in industry etc. to power large electric motors of the sort that are to be found in big cranes. Here are photos of the submarine hatch (from outside), steel door (from inside) and a hinge (from outside the building). It seems clear that the building was used for some very special war-related development work, possibly connected with bombs which were designed to bounce off the surface of water and then detonate at specific depths and water pressures. London Gardens Online says that “Wartime experiments were carried out [in Capel Nelmes, Hornchurch] including development of the bouncing bomb across flooded land.” The building is not far north of RAF Hornchurch, which may well have supplied the necessary labour and expertise. And the soggy Rainham and Hornchurch Marshes lie near the Thames just south of the airfield. There is however no known link with Barnes Wallis and the team who later developed the ‘Dambuster’ bombs. Can anyone help with further information, or suggestions about avenues of investigation that might be followed? (We are already in touch with the War Museum and Kew) If so, please email Martin Stanley .