Getting that M.20 out of a slit trench would not be easy that's for sure. As a matter of interest one of the WD M.20 damper knobs I acquired years ago had the tyre pressures stencilled on in white paint.
No one has picked up on the fact that the front brake lever is set too far away from the throttle twist grip. I doubt you could reasonable reach it and was probably moved when getting the machine into the trench!!
Does he have a panda on his sleeve ? If so, this is probably one of the series of photos of 9th Armoured Division, taken around Newmarket in July 1942.
That photo is in one of the weeklies THE MOTOR-CYCLE or MOTORCYCLING,it looks like the word is SUN with a picture of a flower with stalk,maybe its the name he had for the bike sunflower?