The round tower at Greve de Lecq is Jersey's only coastal defensive tower built on the north coast. Greve de Lecq was seen to be particularly vulnerable to an attack by the French in the late 18th century, so when the Governor of the time Henry Seymour Conway decided to build a ring of defensive towers, Grève de Lecq's was one of the first to be completed in 1780. 
It stands about 100 metres inland in the centre of the bay, and was supported by other defence constructions, a redoubt on the east hill and two batteries on the western headland and in the west of the bay.
An 18pdr was mounted on the roof. It was manned in 1797 by men of the Somerset Fencible Regiment, in 1802 by the Royal Invalid Regiment, in 1803 by eleven men of the 3rd Royal Garrison Battalion and in 1815 by twenty men and 1 x 18pdr carronade. An underground magazine was built for the tower some 61m to the west.
In 1840 the garrison of the Tower was one Sergeant and twelve men. It had a magazine for 24 barrels of powder but it was reported as in very poor repair and needed a new roof.
The tower was altered substantially during the German Occupation with the addition of a concrete floor, and later alterations included a new first floor and stair.
The external ground level has been raised substantially in later years. Like many of the towers today it is painted white on its seaward side and serves as a navigational marker.
It is owned by the States, having been acquired for the public of the island from the War Department on 3 February 1923 for £100. The land surrounding the tower, now a public car park, was acquired in 1938 from Sydney Podro. The car park was not built until 1965.
The tower was used by the Jersey Scout Association between 1993 and 2002 and has also been used by the Jersey Youth Service.
Along with all Jersey's other coastal towers and historic fortifications it is a listed building, described as follows in the Jersey Heritage Historic Environment Record website:
- "Built circa 1779 , the tower is significant as an outstanding example of an integral group of surviving Conway towers in Jersey that not only illustrates the changing political and strategic military history of the Island in the late 18th and 19th century, but represents a turning point in the history of defence strategy across Europe, and global trends in the history of war.
- "Forms part of a fine ensemble of period fortifications at Greve de Lecq, including 1810 barracks and Le Catel Fort. Shown on the Richmond Map of 1795.
- "Standard Conway tower pattern. Round and tapered, built of regular squared and well-tooled blocks of granite. The upper floors are punctuated with musketry loopholes, with dressed granite doorway (blocked) raised at first floor level. There are four machicolations at parapet level.
- "Roof platform with masonry parapet. Retains its iron tripod.
- "Adapted by the German occupying forces in 1940s including insertion of doorway formed at ground floor level via a short descending flight of steps, and concrete first floor at an adjusted level. Late 20th century alterations include new first floor and helical stair."
Click on any image to see a full-size version