In this fuller picture you can see that it is indeed a Matchless G3L and I have posted this as a test picture after signing up for IMGbb.com as suggested in an earlier post.
That's interesting, the 50th Division marking had been very carefully removed on the picture post cover, not unusual from a security point of view but not usually to this standard.
The Driver steering wheel badge with star or crown above isn't often seen on the stripes though, the sergeant appears to be on the front line rather than doing training so I'm not sure that is the answer.
I have asked some badge experts on another forum so hopefully someone will have the answer.
Apparently it was a common practice for sergeant-instructors to wear even semi-official trade badges either superimposed upon or slightly above the rank stripes.
He may not be at the front...By October 1944 large areas of Europe had been liberated...
Even if his unit were 'at the front' he could have been a few miles behind the lines...Training replacement troops perhaps?...Ian
Also every able bodied man was being pushed into the European theatre, even Territorial troops were asked to volunteer, as was my Dad. He was part of a searchlight regiment (formerly the 'Shiny Seventh) London Regt.) stationed in Suffolk for most of the war. When the call for able bodied men came, he went across to Holland to be attached to the DLI and ended up in Cologne. Perhaps the sergeant in the picture was one of the rear echelon called to the front in the same way......
It seems that these drivers badges with stars and crowns above began life in the 1920s as Prize badges awarded to mechanised Royal Artillery units, then in the 1930s other units followed suit.
This practice was discontinued in the second war and they were sometimes worn by instructors. But not usually on top of the stripes.
The steering wheel alone carried on to mark a qualified driver worn on the lower sleeve. Then mid WW2 a steering where with "IC" (Internal combustion) above was created but its unclear how you qualified for each type.
The winged wheel DR MC BC MT ect badges were also worn by drivers but they were unofficial and purchased and worn if allowed by your commanding officer.
He may not be at the front...By October 1944 large areas of Europe had been liberated...
Even if his unit were 'at the front' he could have been a few miles behind the lines...Training replacement troops perhaps?...Ian
It looks like he's got 2 young trainees already
Rik, thanks for posting the photo, and Rob for trying to explain the meaning of it.