U-1407 had been scuttled following the German collapse at the end of the Second World War, was salvaged and eventually commissioned into the Royal Navy as HMS Meteorite.

Explorer and Excalibur were popularly known as the 'blonde' submarines because of their hydrogen peroxide oxidiser and they served a useful purpose as high-speed targets for the Royal Navy's anti-submarine forces.

Additionally, the engine room (which was not occupied while under way) would often be the scene of flames appearing on the top of the combustion chamber, and on at least one occasion the crew were forced to evacuate the pressure hull and stand on the upper casing to avoid fumes which had suddenly filled the boat.

There were so many practical problems with the technology, one Royal Navy submariner remarked that, 'I think the best thing we can do with peroxide is to try to get it adopted by potential enemies'.

[3] When the US Navy succeeded in designing a nuclear reactor suitable for submarine installation, the HTP project was abandoned, and Explorer and Excalibur were scrapped.