London's River Lights

If you walk along the Thames Path, east of Woolwich, you will discover these small red lighthouses. They can be found at Margaretness (or Tripcock Ness), Crossness and Coldharbour.

They are not lighthouses, in the traditional sense, but more like navigational light masts.

The Margaretness Lighthouse was installed in 1902, by Trinity House (the General Lighthouse Authority for England), but has been operated by the Port of London Authority, since 1993. 

In 1566, Queen Elizabeth I empowered Trinity House to set up "so many beacons, marks and signs for the sea whereby the dangers may be avoided and escaped and ships the better come into their ports without peril."

From 1604 until 1987 Trinity House was the authority for licensing pilots on the River Thames.

© Nigel Cox / River Thames: Cross Ness lighthouse

Originally, there were nine land-based unattended lighthouses spread along the River Thames. They were of a steel lattice construction, with the light being 12 metres (39 feet) above the high water level. This is the average height of a ship's bridge. Steel steps led to a platform from where the bulb could be changed and the structure could be assessed. The light can be seen from a distance of 8 nautical miles, and flashes twice in every 5 seconds.

Following a consultation, in 2024, these steel lattice structures were dismantled and removed. The foundations were relaid and new drop-down masts were installed. This allowed for the installation of new light units, while eliminating the need for working at height in a remote location.

The new design of the 8 metre (26 feet) light mast still has a focal plane almost equal to that of the old design, and still retains the brilliant red colour. The fencing, also still retaining its red colour, is secured with barbed or razor wire, to prevent intrusion.

In 2023, the Port of London Authority was managing over 800 pairs of shore-based navigation lights, which are installed along the banks of the River Thames and inlets to guide mariners.