Grace's Guide is the leading source of historical information on industry and manufacturing in Britain. This web publication contains 131,598 pages of information and 209,070 images on early companies, their products and the people who designed and built them.
of Millwall, London and Newbridge Chain Works, Pontypridd
1808 Brown went into partnership with Samuel Lenox
1812 A factory was built in Millwall in 1812.
1816 Brown constructed a hydraulic testing machine for chains at the Millwall works, where anchors, buoys and water tanks were also made.
1816 a second factory was built at Pontypridd, which was to become their main chain works.
1851 Manufactured fire engines for house, factory, and general purposes, to the designs of William Roberts
1852 George William Lenox, of Billiter-square, in the city of London, Chain Cable Manufacturer, and William Roberts (of Millwall), Poplar, Foreman to Messrs. Brown, Lenox, and Co. of Billiter square aforesaid, applied for letters patent for the invention of improvements in machinery for raising and lowering cables and other chains .
1852 William Roberts (of Millwall), Poplar, Foreman to Messrs. Brown, Lenox, and Co. of Billiter-square, applied for letters patent for the invention of improvements in machinery for stopping and lowering cables and other chains .
1858 Exhibited bell buoy
1863 'The workmen in the employ of Messrs. Brown, Lenox and Company, at the Newbridge Works, Pontypridd, have contributed the sum of £20 17s. 8d., in aid of the Lancashire operatives, and which has been forwarded to Mr. Maclure, the Honorary Secretary of the Central Committee, Manchester.'  [The Lancashire cotton workers were suffering hardship because of the American Civil War]
1866 Chain cables and anchors' proving establishment. 
1868 Death of George William Lenox, who had been the senior partner in the firm.
1891 '300 MEN THROWN OUT OF WORK AT PONTYPRIDD. On Thursday, as result of a foolish freak on the part of a person or persons unknown, work had to be completely suspended at Brown, Lenox, and Co.'s Chain Works, Ynysyngharad, Pontypridd, involving the enforced idleness nearly 300 men. It transpires that owing the holidays the works had been closed for the first three days of the week, but the men returned to work at six o’clock on Thursday morning they were astonished to find that the whole of their tools were missing. Welders, tongs, hammers, and other chain makers’ tools had disappeared, and no little consternation was caused. Eventually, after a considerable search, the missing articles were all deposited together at the bottom of a deep well below the water wheel. No clue has yet been obtained to the perpetrators of this extraordinary freak.' 
1914 Admiralty Contractors. Specialities: Buoys and Moorings for the Admiralty. 
The firm supplied all the chain to the Royal Navy until 1916.
By the 1930s the Millwall branch, Brown, Lenox & Company (London) Ltd was producing tanks, buoys and other vessels.
For a time they also occupied the site of Providence Iron Works.
After WWII the firm also occupied new buildings in Westferry Road.
By 1958 The works were in Pontypridd, South Wales, and in Millwall, London, E.14.
1961 Manufacturers of ships' chain cable and anchors, mooring cable, mooring anchors and buoys, steel castings, material handling equipment and steel fabrications. 400 employees. 
By 1964 was part of N. Hingley and Sons
1966 Acquired by F. H. Lloyd and Co
The Millwall works closed in the 1980s.
The company made some stationary steam engines, including a winding engine with two 27" bore cylinders for Dinas Steam Colliery
Located to the east of the River Taff and served by the Glamorganshire Canal, in an area known as Ynysangharad. The canal facilitated the supply of iron from Merthyr and Aberdare. In fact it provided the only transport link for materials and finished products until 1902. Even after this date, chains were taken by canal barge to Cardiff for testing at the proving house.
A feeder from the River Taff to the canal passed through the works, the water being used to drive waterwheels (turbines later). The topography ensured a good head of water for the machinery, noting that the works were sited next to deep double canal locks). The point where the feeder joined the canal also served as the entrance for boats bringing in iron bars, the boats passing under a hump-backed bridge which carried the towpath. Downstream (south) of the locks was another connection to the canal. This branch went into the testing house, from where finished chains and other products could be shipped. On the opposite canal bank was a row of cottages named Chainworks Row. These were provided with good-sized gardens which ran down to the canal.
The above information is from 'The Glamorganshire and Aberdare Canals' Volume 1, which includes an extract from the relevant section of the 1874 25-inch O.S. map, and some old photographs taken from an elevated position, showing the layout of the works in relation to the canal
A map and aerial view may also be found on the Rhondda Cynon Taf Library Service's website 
The Pontypridd works closed in 2000.