Portland Bill Lighthouse is a functioning lighthouse at Portland Bill, on the Isle of Portland, Dorset, England. The lighthouse and its boundary walls are Grade II Listed. As Portland Bill's largest and most recent lighthouse, the Trinity House operated Portland Bill Lighthouse is distinctively white and red striped, standing at a height of . It was completed by 1906 and first shone out on 11 January 1906. The lighthouse guides passing vessels through the hazardous waters surrounding the Bill, while also acting as a waymark for ships navigating the English Channel. History The two original lighthouses, now known as the Old Higher Lighthouse and Old Lower Lighthouse, operated as a pair of leading lights to guide ships between Portland Race and The Shambles sandbank. They were constructed in 1716, both rebuilt in 1869, and decommissioned following the completion of the present lighthouse. At the turn of the 20th-century, Trinity House put forward plans for building a new lighthouse at Bill Point. They acquired the required land in 1903. The builders, Wakeham Bros. of Plymouth, began work on the foundations in October 1903. Chance & Co of Birmingham supplied and fitted the lantern. A pressurised vapour paraffin lamp was used, placed at the centre of a large (first-order) revolving optic; weighing 3.5 tons, this was made up of four asymmetrical catadioptric lens panels and a concave prismatic reflector. The lighthouse was completed in 1905 at a cost of £13,000, and the lamp first lit on 11 January 1906. A red sector light was provided in addition to the main light, shining from a window in the lower part of the tower, to indicate the position of The Shambles. The light was electrified in the mid-1950s. In 1940 the lighthouse was provided with an F-type diaphone fog signal, sounding from a window part-way up the tower. Compressed air was provided to six cylindrical storage tanks by a pair of Reavell compressors, all located (together with a standby generator) within the base of the tower. These were connected at a higher level to the sounding tanks, which fed the compressed air to the diaphone itself, mounted behind its trumpet-like emitter which protruded through the window. Admission of air into the diaphone was controlled by a clockwork (later electric) coder, which caused the diaphone to sound a 3.5-second blast every 30 seconds. The 180 Hz note had an audible range of (which could be