30th October 1724

The first lighthouses were built on the Casquets

The Casquets, a series of large rocks due west of Alderney, have long been recognised as a threat to shipping. So it was that in 1724 the rocks’ owner, Thomas Le Cocq, built three lighthouses under license from the British lighthouse authority, Trinity House.

Why three rather than just one lighthouse? In order to help ships navigate, Trinity House wanted to make the lights on the Casquets distinctive so they wouldn’t be confused with those on mainland England or France. They were therefore arranged such that the lights themselves would form a horizontal triangle.

Le Cocq earned half a penny for every ton of shipping that passed by them safely. £50 of this would be sent to Trinity House in exchange for the license to operate the lights.

Called Donjon (some say Dungeon), St Thomas and St Peter, the fires on the top of each one were initially lit by coal. In 1790, five years after Trinity House had taken ownership, they were converted to oil.

Casquets lighthouses

Initially, they didn’t flash the way lighthouses appear to do now since there were no moving parts. However, clockwork rotating dishes were installed almost 30 years later to send out a beam across the sea. Managing these was labour-intensive as the mechanism would only run for 90 minutes before it needed to be wound up again.

Changing configuration

Today there is only one lighthouse on the Casquets, as has been the case since 1877. In that year, the westernmost tower was raised and the other two were switched off.

The remaining tower is 23m tall, putting the light 37m above mean high water when the height of the rocks is taken into account. It was electrified in 1952 and automated in 1990. Being so far off shore, it is powered by solar panels and wind turbines, which are sufficient to cast the beam of its LED lights 18 nautical miles.


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Other events that occured in October

Guernsey Post Office was established 1st
Guernsey switched to Reichsmarks 2nd
Sark was the target of Operation Basalt 3rd
Sark voted for democracy 4th
Guernsey lifeboat saved a Swedish schooner 5th
Jeeves actor died in Guernsey 6th
Sarnia Theatre celebrated its most successful year 7th
The Story of Adele H opened in cinemas 8th
Howards’ Way came to Guernsey 9th
Guernsey Ladies’ College opened 10th
A Trislander ate itself between Jersey and Guernsey 11th
The Channel Islands’ king set sail for England 12th
Major General Sir Isaac Brock died 13th
Footballer Matt Le Tissier was born 14th
Island FM brings commercial radio to Guernsey 15th
Channel Television saw off a rival broadcaster 16th
The first mines were dug on Sark 17th
Sark’s Stocks Hotel was damaged by fire 18th
Elizabeth College’s foundation stone was laid 19th
Hitler ordered the Channel Islands’ fortification 20th
Guernsey’s stone crackers demanded a pay rise 21st
The desalination plant opened 22nd
Sir Charles Hayward buys Jethou for £91,000 23rd
Guernsey Monopoly board game went on sale 24th
Dame Sibyl Hathaway chose her Desert Island Discs 25th
GUNS founder Charles Machon died 26th
Bailiff Sir Peter de Havilland was born 27th
A man “disappeared” from a Guernsey ferry 28th
Express & Star bought Guernsey Press 29th
The first lighthouses were built on the Casquets 30th
States of Guernsey voted to lower the voting age 31st