Rootes group trading name was Commer and they made a turbo charged 3 cylinder engine with 6 pistons, about 105 horse power and torque out put of some thing like 270 lb.ft at 1200 rpm. It was known as TS3 but in every day language it was called a Commer Knocker, they were popular in road transport in Australia as vehicle registration was calculated by the number of cylinders the vehicles engine had. I drove trucks with this engine in the 1960's, believe it or not they were also used in semi trailers on interstate transport. Un-believably under powered and on a good day with a gross mass in the 20/ 22 ton range you'd be very lucky to exceed a top speed of 35 miles an hour, that's if you ever got into top gear. Even a slight head wind or in undulating country would see the truck down to 2 nd gear in the gear box and low in the two speed axle. Although I never found a hill on the highway it couldn't climb. An interesting thing is that at night when struggling against a head wind or going up hill there was a long flame and sparks coming out the exhaust, being Australia it was quite common to have a spark arrester in the tailpipe. The closest capital cities in Australia is Adelaide --- Melbourne at around 460 miles, can you imagine the hours you needed to stay awake to physically load and unload and do the return trip. No sleeper cabs in those days, when your eyes wouldn't stay open you'd put a cushion or rolled up blanket on the steering wheel and get a couple hours sleep. As we were paid trip money to make a weeks wages you'd need to do at least 2 return trips a week. That considered I spent most of my working life as a truck driver.Didn't Commer have a lorry engine with these in the '50s? I think it was a 6 cylinder and a flat configuration. Might not be right I was only 10 and more interested in bicycles.