A desk of official figures

Five working lights, with the numbers their authorities published on the pages cited, checked on 15 November 2026.

A black-and-white banded lighthouse beside white keepers’ houses under a blue sky, with a warning sign about freak waves in the foreground — Hook Head Lighthouse, County Wexford, 14 December 2007. Photograph by Athena (Flickr), CC BY 2.0. The black-and-white bands and the painted warning about freak waves are part of the working station as it stood that day.Photo: Athena (Flickr) · CC BY 2.0 · Commons

Bishop Rock Lighthouse was built by Trinity House in 1858, and further strengthened in 1887, four miles west of the Isles of Scilly.⁠¹ Trinity House describes the rock ledge as 46 m long by 16 m wide.⁠¹ Longships Lighthouse was built by Trinity House in 1875, to replace a shorter tower on the rocks at the extreme south-west of Britain’s mainland.⁠²

Station	Authority	Character	Range	Tower	Height of light	Notes from the same page
Eddystone	Trinity House	Fl (2) 10s	17 NM	49 m	41 m above MHW	4th order (250 mm) rotating; automated 1982
Bishop Rock	Trinity House	Fl (2) 15s	20 NM	49 m	44 m above MHW	Hyper-radial (1330 mm); intensity 60,000 candela; automated 1992
Longships	Trinity House	Fl (2) WR 10s	15 NM	35 m	35 m above MHW	1st order dioptric; intensity 14,400 candela; automated 1988
Fastnet	Irish Lights	Fl W 5s	18 NM	54 m	54 m above MHWS	Present granite light established 27 June 1904. A 1969 electric range of 28 NM is historic.
Hook Head	Irish Lights	Fl W 3s	23 NM	35 m	46 m above MHWS	Also exhibited by day in poor visibility

Figures as published by the authority on the pages cited, retrieved 15 November 2026. NM is nautical miles. MHW is mean high water; MHWS is mean high water springs, the wording Irish Lights uses.

Irish Lights records that the light was converted to electric on 10 May 1969, and then had a range of 28 nautical miles and a power of 2,500,000 candelas. Those are historic figures: the range published on the same page today is 18 nautical miles.⁠³ Fastnet Lighthouse was automated and converted to unwatched at the end of March 1989.⁠³

Bell Rock and Minot’s Ledge have a place on the history page, with measurements from the 1911 Britannica. They are not in this desk, because this desk is only for characters published today by Trinity House or Irish Lights.