A little history:
In 1906 a second lighthouse, which would become known as Lower Pencarrow, was erected at the bottom of the Pencarrow cliffs. It was designed to be used when fog, or cloud, obscured the upper level light, and also to work with the upper light as a day mark.
In latter years the presence of the fog signal would prove more significant to those living at the lighthouse than the light itself. Its presence ensured an ongoing role for a keeper after a new automated lighthouse at Baring Head became operational in 1935 and Pencarrow was used solely as a day mark.