In the 1860s Lavernock Battery was built, with guns to protect the approaches to Cardiff.
On 18 May 1897, Guglielmo Marconi, assisted by George Kemp, a Cardiff Post Office engineer, transmitted the very first message by wireless telegraphy — radio — across the water between the island of Flat Holm and Lavernock Point, a distance of 3.5 miles (5.6 km). The message sent in Morse code was ‘ARE YOU READY‘.
A line drawn between Lavernock Point and Sand Point, Somerset marks the lower limit of the Severn estuary and the start of the Bristol Channel. Because of the extreme tidal range there are very strong currents or rips close inshore to the point with speeds that exceed 7 knots (13 km/h) for several hours at each tide.
Various proposal have been put forward to construct a Severn Barrage for tidal electricity production from Lavernock Point to Brean Down in Somerset.