This helmet survived the cull my collection went through a few years ago, mainly because I hadn't managed to identify what TRO stands for.
It's a BMB (no visisble date) helmet with a BMB 1939 liner, in obvioulsy poor condition. The helmet was original black, the outside was painted white/cream at one point and has some marking on the front which I can't make out. This has been overpainted in yellow and the T.R.O. added back and front.
The strap fixings are off center and have been punched again but as a mirror image, and off center again. Somebody has attempted to clean or preserve it with some sort of oil which has dried, I haven't bothered to clean it.
The only yellow painted helmets I know of are the Gas Identification Officers, I have also seen a black one for sale on e-bay (below) a few years ago.
Does anybody know what it could be?