Milford Haven has long been recognised by merchants and shipowners as one of Britain's finest deep water harbours; today, large fleets of trawlers and oil tankers gather in the anchorage. Dangerous reefs lie just below the surface of the approach to this famous port, almost in mid channel and in two groups through which shipping must pass.
One of the greatest dangers—the dreaded Crow Rock and Toes lying off Linney Head—lies some seven miles south-east of St. Ann's Head, which has claimed many more vessels than the reefs within the harbour. Today, two usable channels are marked clearly by sets of leading lights, all vital to safe navigation.
Trinity House approved in principal a private application to build a coal-fired light at St. Ann's Head in the second half of the 17th century to guide Milford-bound shipping; it was to be supported by voluntary payment of dues. However, the owners extracted dues illegally from shipowners and the light—the only one on the west coast—was discontinued. 40 years passed before another light was established although it is said that sea traders petitioned many times for the area to have lights.
On 15 March 1712 a patent was granted to Trinity House to build a lighthouse at St. Ann's Head. Trinity House in turn—as was its policy at the time—leased it to the owner of the land, Joseph Allen, who agreed to build two lighthouses and keep them in good repair. The terms of the lease were for 99 years at an annual rent of £10; to help maintain the lights, Allen was permitted to collect dues from the shipmasters at Milford Haven amounting to one penny per ton of cargo on British vessels and two pence on foreign vessels. Allen established two towers near the old disused lighthouse and lit coal fires on them in June 1714.
Robert Stevenson visited the station in 1801 and describes them as leading lights guiding vessels clear of the Crow Rock off Linney Head and that:-
“The light is from Argand burners with parabolic silvered copper reflectors each twenty and a half inches in diameter. In the one lantern there are 16 reflectors and in the other 11 and though they are only about one hundred paces distant from each other there is a distinct keeper at each lantern, so that they are in the most complete state of cleanliness and good order.”
The front (low) light was rebuilt in 1844, when cliff erosion endangered the old tower, the new one being situated nine metres or so from the cliff edge. When the rear light was discontinued in 1910, a Matthews burner was installed in the front light, and in 1958 the station was converted to mains electricity with generators for standby.
St. Ann’s Head Lighthouse was automated and demanned in 1998. The lighthouse is now monitored and controlled from Trinity House’s Planning Centre in Harwich, Essex.