Well you could always ask these blokes, im sure they would know The History of the British 7th Armoured Division - Desert Rats also note the variants of the 'Rat' on their page
Hi, personally I would not be happy with this being an originally unit painted desert pattern helmet either. The outside appears to have been "aged" differently to the inside. I think the seller has just given you a bit of "misinformation" regarding the Australian link, just to give you the impression that he does not know he is selling you a super rare gem of a helmet (not)! Leon.
"Always do sober what you said you'd do drunk. That will teach you to keep your mouth shut." Ernest Hemingway
I´m collecting combat knives, and bayonets, not helmets.
The asked amount of the helmet was a low double-digit one and was in the parcel I received, together with some neat bayonet´s.