The outcome of the various experiments and modifications made to the A1s in the late 1920s was a new Class A3 "Super Pacific", the first example of which was number 2743 "Felstead". This locomotive appeared in August 1928 with 220 psi (1.52 MPa) boiler, 19-inch (483 mm) cylinders, increased superheat, long-travel valves, improved lubrication and modified weight distribution. Another new development was the changeover from right- to left-hand drive, less convenient for a right-handed fireman, but more so for sighting signals, resulting in the modification of all earlier locomotives.