It was circular, of solid construction, about forty feet in diameter and the same in height. In 1796, with a garrison of 38 men and three not very large guns, it had withstood attack from two warships of the British Navy, one with 74 guns, and one with 32. The Board of Ordnance were so impressed by the tower's resistance to fire-power, that they adopted the design for their own towers. These too were round, or oval, and in their construction used up to a million bricks, most of which came from near London. The Aldeburgh Martello Tower is the exception, because instead of being round, it is quatrefoil in shape: in effect four towers fused into one. The reason for this is not recorded. It might have been a piece of lateral thinking resulting from the quatrefoil arrangement of a platform for four guns; or, as has been suggested by Sheila Sutcliffe in her book Martello Towers (1972), it might have been an earlier design proposed for the Dymchurch Wall in Kent in 1804 but never built.
The tower was designed for four guns, although in 1815 it was noted that there were only two 24-pounders there. These were fired over the parapet, off timber gun carriages shackled to ring mounts which still hang from their stone blocks. In the late nineteenth century, new guns were provided, with rifled barrels for more effective fire. The old guns, of which there were by then four, were sunk into the roof to act as pivots. The tower would have been garrisoned by the local Volunteer Artillery. On the main barrack room floor, there were double berths for eight soldiers, and single berths for five NCOs. The northern bay was partitioned off with a canvas screen, to provide a private room for the officer in charge. There were two fireplaces for cooking. The lower floor was used for storage - coal, water, food and ordnance. The powder magazine was reached by a separate stair, but lit by a window from the main store. It was placed on the landward side, for safety.
The tower did not originally stand on its own as it does today. It was once part of the village of Slaughden, of which the last houses survived into this century, but finally vanished due to erosion before the last War. The sea has also swept away part of the moat surrounding the tower itself, until stopped by the building of coastal defences of a different kind in the 1950s. In 1931 the tower, by then abandoned and derelict, was sold by the Ministry of Defence to a Mr Walter Wenham. Over the next few years it was occasionally used by the Mitford family for camping holidays. Then in 1936, it was sold to Miss Debenham, who commissioned the architect Justin Vulliamy to convert it into a studio. This was done very carefully by adding to its top an elegant penthouse, hardly affecting the interior or original structure of the tower at all.
By 1971, the Thirties penthouse had in turn become derelict, and the tower itself was badly in decay. This time it was acquired by the Landmark Trust. Extensive repairs were carried out, and the tower itself converted to provide holiday accommodation.