He designed several different 7 ft (2,134 mm) broad-gauge types for the growing railway, such as the Firefly 2-2-2s and later Iron Duke Class 4-2-2s. In 1864 Gooch was succeeded by Joseph Armstrong who brought his standard-gauge experience to the railway. Some of Armstrong's designs were built as either broad or standard gauge just by fitting different wheels; those needing tenders were given old ones from withdrawn broad-gauge locomotives.[81]