 Historically, Lihou was an important location for a commercially significant industry based around the harvesting of seaweed (or vraic in the local language, Guernésiais). Records suggest considerable activity as early as the beginning of the nineteenth century. The value of the seaweed as a fertiliser was so great that in 1815 Eleazor Le Marchant, lieutenant bailiff of Guernsey and owner of Lihou, initiated a court case to prevent islanders from drying seaweed on the beaches of Lihou. The case eventually led to new regulations issued in 1818 by the Bailiwick legislature, known as the Chief Pleas at the time, based on a review of ancient royal decrees. However, the Royal Court of Guernsey ruled in favour of the islanders in 1821, with the effect that permission to harvest seaweed on Lihou was granted to inhabitants of the parishes of St Peters and St Saviours. More than a century later, in 1927, a factory was established on the island to produce iodine from the seaweed.
