It was during Churchward's tenure that the term "Locomotive Superintendent" was changed to "Chief Mechanical Engineer" (CME).[82] Charles Collett succeeded Churchward in 1921. He was soon responsible for the much larger fleet that the GWR operated following the Railways Act 1921 mergers. He set about replacing the older and less numerous classes, and rebuilding the remainder using as many standardised GWR components as possible.