I look forward to seeing the reverse of the photo when IMGbb sorts itself out !

Is it 47278 on the number plate ? That would fit with an impressed block. I wonder if the serial on the tank is a 'movement' / 'embarkation' number. It should be on the front, but BEF units famously mis-interpreted instructions on markings...or is that a white GHQ arm of service bar on the lower edge of the tank ? BEF serials only went to '231' though so it isn't that but maybe the space was still blank and the movement serial not yet overpainted ?

look at the top "tube" closely its actually his gauntlet as it splays out to the widest part.....

email (option): taybrig@shaw.ca

ImgBB finally works again. The back of the photo:

email (option): wdmotorcycles@gmail.com