In 1874, Cudworth was appointed Locomotive Engineer of the SER, with Alfred Watkin, son of SER chairman Sir Edward Watkin appointed Locomotive Superintendent at a salary of £500. Cudworth was not one who was disposed to toe Watkin's line, which put a strain on their relationship. In 1876, Watkin persuaded John Ramsbottom of the London & North Western Railway (LNWR) to design a number of 2-4-0 passenger engines for the SER, unbeknown to Cudworth. Orders were placed with Sharp, Stewart of Manchester and Avonside of Bristol for ten engines each. The locomotives were very similar to the LNWR's Precedent Class locomotives. Known as the Ironclads, they replaced the Singles on the boat trains for a short time, but were quickly relegated to less prestige duties and the Singles resumed their former role. When Cudworth found out about the engines, he was furious and resigned. It was considered by many on the Board of the SER that Cudworth had been sacked.
