An article from the Welshman dated 17th January 1845 described the construction of a gasworks in Rhymney “Gas works have lately been erected at Rhymney iron works. The new light has been introduced in the principal shop., public houses, offices, &c. The improvement is very generally appreciated by the inhabitants.” The Rhymney Gas Co. Ltd. was formed in 1863. Complaints were being made about the Rhymney gasworks in 1860 “small gasometer here, capable of supplying a limited number of shops and offices, but, somehow, we are left in fits of periodical darkness” (The Cardiff Times 28th December 1860). In 1867 The Rhymney gas company had fixed several gas lamps in public thoroughfares, they also fixed eight gas lampposts and six gas lamps on brackets in Pontlottyn in 1876. In 1880, the manager of the gasworks was a Mr Stockwell. A great storm in March 1898 which affected South Wales, severely damaged one of the gasholders at the Rhymney gasworks. In 1898 the Rhymney & Aber Valleys Gas & Water Act incorporated that Company and authorised it to acquire the Rhymney Gas Co. The Rhymney & Aber Valleys Gas & Water Co was formed in the same year. The annual gas production in 1900 was 12m cu.ft. of 15cp gas (14 prescribed) from 1,120 tons of coal. Sales 10,300,000 cu.ft.. 8 miles of mains. W. Hiley, Chairman. David Lewis, Engineer & Secretary (The Gas and Water Companies' Directory and Statistics). 1930’s taken over either directly by UK Gas Corporation (and put under the management of the Rhymney & Aber Valleys Gas & Water Co.) or controlled by Rhymney & Aber Valleys prior to UKGC takeover. In the 1930’s the company was supplied with purified coke oven gas at 425cv in bulk from Bargoed pre-1938. Annual gas production in 1914 was 158.7m cu.ft. of 14cp gas (including water gas) from 4,066 tons of coal. Benzol enricher used. [these figures appear to combine the gas made at Mill Road (Caerphilly) and perhaps Pontlottyn with the coke oven gas purchased] 84 miles of mains. J. Prosser Jones, General Manager & Secretary, Barton Grainger, Engineer. By 1914 the Company supplied Rhymney, Caerphilly, Bedwas, Llanbradach, Hengoed, Bargoed, Aber Bargoed, Maesycwmmer, Fleur-de-lis, Pengam, Gwerthonor, Pontlottyn, Gelligaer, Deri, Bedlinog and the Aber Valley. By 1930, no gas was being made by the Company. Bulk supplies of coke oven gas provided by the Company were used by Bedwellty UDC to the exclusion of their own plant. Bedwellty in turn sold much of this gas to Mynyddislwyn UDC who had taken over part of Bedwellty 's network and did not build a works of their own. Control was acquired by the United Kingdom Gas Corporation, their 'Rhymney & Aber Group' also included the Merthyr Vale gas works and the Quaker's Yard Gas & Water Co. All three companies were under the same Caerphilly-based management by 1938. In 1938 the annual purchase of coke oven gas was 259m cu.ft.. In 1949 671m cu.ft. of coke oven gas purchased, no gas manufacturing plant. B. Grainger Engineer, Manager & Secretary. In 1952 the “Gas World Year Book”, showed that Rhondda purchased 650m cu.ft. of gas Coke Oven gas and E. Jones was the engineer and manager. By 1955 the supply of 475cv gas from the new Nantgarw coke ovens had taken over the whole Rhymney & Aber Valleys grid, via a new 18" main from Nantgarw to Caerphilly. Tredegar was connected at the northeast end and there was a link to Merthyr Tydfil and Dowlais but a valve was closed at the junction with the R&AV line. Bargoed ovens were still supplying 425cv gas, but only to the Bargoed district, Deri and over the mountain to Bedlinog. Two spiral gasholders were in use at Caerphilly in 1974 and 1982. The undertakings records are held at the Glamorgan Archives.