The low light lighthouse now in use dates from 1844. It apparently replaced another built in 1800 which was incorrectly sited too far eastward. The tower is a squat octagonal 12.8m (42ft) high building. Its red sector covers the Crow and Toe Rocks.

Event and Historical Information
In 1798 John H. Allen made an application for an advance of £500 on account of the £2000 which Trinity House had agreed to make available to build a new lighthouse. In May 1800 it was reported that the alterations and improvements had been completed. Trinity House's Captain Huddart went to inspect the work in the same year and was in general satisfied. However the new southern lighthouse was placed somewhat to the eastward of the site he had recommended, but as this could not lead ships nearer to any danger than some 510m (560yds) when the lights were lined up by shipping, he thought that it was not material. Details of the low and high lights, their elevation and their distance apart (186m or 203 yds) are given in The New Seaman's Guide and Coaster's Companion of 1821. In 1844, the low light was rebuilt was and used in conjunction with the high light (see NPRN 240933 )of 1800 until 1910. Both towers had coal braziers. The existence of a large building, apparently with an enclosed courtyard, near the present compressor-house, is recorded on the tithe map of 1847. No trace of it is to be seen on the first large-scale (1:2,500) Ordnance Survey map of 1875. The keepers' houses built with the 1844 lighthouse have been replaced by the present range of dwellings to the north-east. More recently the old foghorn had been replaced by an electrically operated one. St. Ann's is one of only two old lighthouses in Wales that remain as manned stations, serving as a control point for the remote surrounding lights at Skokholm and South Bishop Islands, the Smalls Rock, Strumble Head and on the automatic St. Govan's Lightship.

Sources include:
Hague, D, 1994, Lighthouses of Wales: Their Architecture and Archaeology, pg49-52
G. Owen, The Description of Pembrokeshire, ed. H. Owen, Vol.11., pg551.
Trinity House Court Minutes, 1661-65.
Whormby, J, An Account of the Corporation of Trinity House of Deptford Strand. (1746; London, 1861).
Trinity House Court Minutes, 21 May 1713; 6 December 1798; 1 May 1800; 7 August 1800; 26 June 1800; 6 May 1813; and 7 May 1844.
Royal Commission Report on Lights, Buoys & Beacons, 1861, pg101.

Maritime Officer, RCAHMW, June 2009.