Hi Paul,
I did turn up some info, but did not take note where from, where South Eastern Command was disbanded just after the war and absorbed within Southern Commnad and Eastern Command. Later on and I think this would be in the 1960's, South East District came into being with HQ at Aldershot.
The attached photo is of a shield for a Service competition, the "Tiger" was actually cut out from a waterslide transfer as used on the vehicles, but have just realised that the area around the head has been filled in with black paint, where on yours I think it shows orange. There looks to be a slight variation between this one and the one on your Rover. I do have another one somewhere, that was the self adhesive sticker type and that was plainly different in details.