This initial proposal also failed but negotiations resumed in 1736 when 60 soldiers drowned after their vessel crashed on the Wolves rocks near Flat Holm.

A 3 m (10 ft) tall crack on the side had to be repaired as did the oak beams supporting the top platform.

Flat Holm Lighthouse was the last signal station in the country in private ownership.

[8] The siren was originally powered by an 11 kW (15 hp) engine, which gave two blasts in quick succession at two-minute intervals that could be clearly heard by people living on both coasts but for many years following World War II, the foghorn was heard as one long and one short blast and nautical almanac data as at 1965, stated that the interval was 1.5 minutes.

[9] Volunteers from the Flat Holm Society, with help from the Prince's Trust, restored the horn and engines in the 1960s.