In 1806, as the Napoleonic Wars impended, Lord St. Vincent commissioned John Rennie and Joseph Whidbey to plan a means of making Plymouth Bay a safe anchorage for the Channel Fleet.

This task required great engineering, organizational and political skills, as the many strictly technical challenges were complicated by the significant resources devoted to the project, from which various parties evidenced a desire for advantage.

Designed for the Admiralty by Walker & Burgess, construction of the granite tower began on 22 February 1841 and was completed on 9 November 1843; William Stuart was superintendent of the works.

[7] The lighthouse had been provided with a second-order catadioptric lens array by Henry Lepaute of Paris;[5] it showed a fixed red light with a white sector indicating an anchorage to the north-east[8] (later the colours were reversed).

[9] Since 1854 a second white light has also been displayed, from a window lower down in the tower, indicating a channel between two hazards: the Draystone and the Knap; it used a small, sixth-order dioptric lens.

Following departure of the resident keepers, the light was monitored from the Trinity House fog signal station at nearby Penlee Point.

Designed by Captain Siborne, work on the oval masonry sea fort started in 1861 and the main structure was completed in 1865.

After several changes in plan, the fort was finally armed in 1879 with fourteen 12.5-inch and four 10-inch rifled muzzle-loading guns in armoured casemates.