Les Hanois

Chance Brothers built the light using 672 pieces of glass. The lens was designed by James Chance and inspected by Michael Faraday who gave it his unqualified approbation.  It was a sixteen-sided revolving catadioptric optic of the first-order, which displayed a red flash every forty-five seconds and was visible at 13 nmi (24 km). The red colour was achieved through fitting a ruby glass chimney over the multi-wick oil lamp at the centre of the lens.

The tapered granite tower, painted white, is notable in terms of lighthouse engineering because it was the first to be built with all the stones dovetailed together both laterally and vertically, thereby making the construction a single solid mass.  The cement mortar in the joints formed between stone faces lock the dovetails so that the stones cannot be separated without being broken. This method, used for the first time at the Hanois Lighthouse, became the pattern adopted for subsequent lighthouses built on sea rocks. The cement was a quick drying type invented by John Smeaton.

The resident engineer was William Douglass, the 28-year-old son of Nicholas Douglass, an engineer, who had suggested using the Dovetail joint for the stones.  The lighthouse was constructed in Cornish granite rather than stone from Guernsey. Cornish masons were employed to dress the stone on the castle pier in Saint Peter Port Harbour, with the finished numbered stones taken by barge to the site. Construction workers on the lighthouse worked in gangs of 16 and when resting were accommodated in Fort Grey. The men being employed to build the lighthouse keepers cottage at Portelet when the weather was bad.

The foundation stone was laid on 14 August 1860 by the Bailiff of Guernsey with several Jurats also present as well as a crowd on a flotilla of local boats.  By March 1862 the tower was 60 ft high. In August they were ready for the light which arrived in October however completion was slightly delayed by bad weather, with the light lit for the first time in late November. Final commissioning was in late 1863, the cost being £25,296.

In 1905 the colour of the light was altered from red to white; it continued to flash once every 45 seconds, but now shone more powerfully. The fog bell was still in use, sounding once every 15 seconds when required. From 1915 an explosive fog signal was sounded in addition to the bell: it consisted of a gun-cotton charge electrically fired. If needed it would be let off every 2+1⁄2 minutes, each charge had to be hung outside the tower from a jib, which was wound up to avoid the blast breaking the glass.

During World War II the light was kept operational until the keepers and their families were evacuated on 21 June 1940. German forces occupied the lighthouse in July 1940 but it was not lit again until September 1945, after the liberation, because the optic had been slightly damaged by gunfire. The Trinity House cottages at Portelet were occupied by troops during the war.

In 1964 the light was electrified, a filament lamp replacing the paraffin vapour burner previously in use. After more than a hundred years of service, the old optic was removed from the tower and presented by Trinity House to the new Pilkington Glass Museum (Pilkington Brothers having gained a controlling interest in the firm of Chance Brothers, the original manufacturers). In its place a smaller (fourth-order) rotating optic was installed, which displayed two white flashes every five seconds. A fog horn, sounded by compressed air, was also installed as part of the upgrade.

The helicopter pad on top of the lighthouse was built in 1979.[

The lighthouse was demanned in January 1996 following automation. At the same time it was converted to work from solar power. This required a slowing down of the optic, changing the character of the light, so as to reduce the power requirement while maintaining the 20 nmi (37 km) range required. As part of the automation process, the compressed-air fog signal was replaced by an electric emitter.