The Royal Navy refers to some shore establishments as "Stone Frigates", because they are subject to the same naval discipline as warships, and are given ship's titles.

For a short period at the end of World War I, Osea Island was such a base, predictably referred to as "HMS Osea". Its inaccessible location made it ideal for the development of a new weapons system – the Coastal Motor Boat (CMB).

The development of small and powerful engines meant that small boats could be propelled at high speed, and the recent development of the torpedo mean that they could carry a weapon that was deadly to large and powerful warships, and use their speed and small size to escape their defences.

Most nations used these vessels for coastal defence against superior opponents. Indeed, similar sized boats are used for this purpose to this day, and Iran currently deploys hundreds which are used to "swarm" American and other warships near their waters.

But the Royal Navy had something more daring in mind – they planned to use the boats offensively to travel over minefields and attack German ships in their bases.

HMS Osea had some forty boats, each forty feet long and carrying a torpedo in a trough at the rear. The latter had to be released astern of the boat, which then had to manoeuvre wildly to avoid being sunk by its own torpedo!

Extensive boat sheds, wooden barrack buildings (some of which can now be seen relocated to Heybridge), rails and slipways were built, and a garrison of sailors and Wrens established.

Visits "ashore" across the tidal causeway required a shore pass, and a Captain Dennis recalled that visits to the King's Head were popular, with sailors invariably "just missing" the low tide for their return, and having to stay overnight!

Although these boats were often seen exercising in the Blackwater and further afield, they saw little action in the Great War because by 1918 the German Navy was a spent force.

But in 1919 the boats were given a special secret mission – to enter the Baltic and ferry British agents to and from Bolshevik Russia. In the process, Lieutenant Augustine Wellington Shelton Agar led a mission into Kronstadt Harbour, sinking two Russian battleships and a depot ship. For this he received the Victoria Cross.

These tiny boats evolved into the much larger Motor Torpedo Boats and Motor Gun Boats of World War 2. Although Osea Island was under army occupation in World War 2, Maldon boat-builders were to do their share building the new gunboats for the coastal forces.

I am indebted to Steven Gridley and Maldon Museum for their "Penny Farthing" newsletters for inspiring this piece. You can find their website here.

Goldhanger in the Past here. also has an excellent section on HMS Osea, including pictures of many of the buildings in their current locations.