Commer TS3 Knocker Transporter

I had no idea these things had two-stroke diesel engines!
Here's what it would have sounded like driving down the road.
• Commer TS3 2 Stroke Ta...
and here's the engine itself - • Commer TS3 knocker motor
6 pistons in 3 cylinders arranged in a triangle.....a smaller version of the Deltic train engine