The founder, Richard Thomas (died 1916), leased two tinplate works in Gloucestershire: Lydbrook in 1871 and Lydney in 1876.
In 1870, Alfred Baldwin bought out his relatives to become the sole proprietor of the firm, but continued to trade under the old name.
The firm was incorporated as EP&W Baldwin Ltd in 1898, and gradually acquired a number of tinplate works, mainly in South Wales.
Under Conservative rule in 1953 it passed to the Iron and Steel Holding and Realisation Agency in readiness for privatisation.
The major event during public ownership as a separate company was the official opening in 1962 of the Spencer Steelworks at Llanwern, a wholly new plant on a greenfield site to the east of Newport.