doubled under favourable conditions). The diaphone remained in regular use as an aid to navigation until 1995, when it was replaced by a high-frequency electric fog signal (sounding from another window, further down) in readiness for automation. On 18 March 1996, Portland Bill Lighthouse was demanned, and all monitoring and control transferred to the Trinity House Operations & Planning Centre in Harwich. The original Type F diaphone was decommissioned in 1996, but in 2003 Trinity House restored it to occasional use for the benefit of visitors; (it was sounded regularly for half an hour on Sunday mornings, except when foggy, until 2017). In the early 21st century the lighthouse used a 1 kW MBI lamp together with the same rotating lens system that had been in use since 1906. (It flashed four times every 20 seconds with an intensity of 635,000 candelas and a range of 25 nautical miles.) The fog signal was used in times of bad weather; it gave a four-second blast every 30 seconds with a range of 2 nautical miles. In November 2018 Trinity House applied for (and obtained) planning permission to remove the lamp and optic from the lantern room as part of a programme of modernisation. It proposed relocating the lens array to the base of the tower, which led to the removal of the historic diaphone fog-signalling equipment, installed there in 1940 and still in working order, on the basis that this was 'the only available [space] for retaining the historic optic on-site'. Present day In 2019-2020 a new non-rotating LED light source was installed in the lantern room and a new omnidirectional fog signal was installed on the exterior lantern gallery (replacing the electric emitter installed in the 1990s). The two LED lanterns (one of which is used, the other kept on standby) have a reduced range of . Tourist attraction As Portland's prime attraction, the Portland Bill Lighthouse is open to the public for tours. A visitor centre is housed in the former lighthouse keeper's quarters. The original centre closed in 2013 due to lack of funding, however a new renovated centre opened in 2015. The tours operated at the lighthouse last approximately 45 minutes and visitors are able to climb the 153 steps to the top of the lighthouse. Gallery See also List of lighthouses in England References External links Trinity House 1906 establishments in England Lighthouses completed in 1906