The earliest lights in which the gas was lit directly from an open-ended tube were very inefficient. To increase the amount of light produced, iron caps with several holes were introduced. These burners quickly corroded and the light output fell accordingly. They were known by the shape of the flame that was produced and given such names as batswing, cockscomb, cockspur, and rat-tail.

The first gas works in the U.K. were built for the Gas Light and Coke Company, that was established in 1812 to light the City of Westminster. The company was formed by Frederick Winsor from Germany, who had previously worked in France for Philippe Lebon. 

The company’s chief engineer was Samuel Clegg, an ex Boulton and Watt man. In 1817 he installed a gas works at the Royal Mint and developed an efficient gas meter. By 1819, 288 miles of pipes had been laid in London to supply 51,000 burners. 

Within ten years most of the country’s larger towns and cities were lit by gas.

Early gas retorts were made of iron in the form of a horizontal tube about 12" in diameter. Each tube was filled with coal and emptied, after producing the gas, through an iron door called the mouthpiece. It was very hard and dirty work. After prolonged use, the retorts would often distort badly and so in about 1822 clay retorts with iron lids were introduced. Filling and emptying the retorts through the single door was a slow process. 

To speed things up George Lowe developed his through retort in 1831. This had a door at both ends, allowing the retorts to be filled at one end and emptied at the other.