Can anyone ID this helmet? (not strictly aero)

Hi Group,

Going to be putting this on Ebay, but I wanted to put together a good description…

Photos: https://picasaweb.google.com/Scott.Bouch/BritishArmyTankHelmet#

No matter how much I use Google, I simply cant identify this particular model, or have any idea of the era / dates of service.

It’s unusual as it’s a one-piece helmet, most use a separate headset / helmet shell.

It’s comms plug fits Clansman style radios, it’s made by Racal / Amplivox, and is intended for armoured vehicles / tanks etc…

Any help would be greatly appreciated. I paid about £60 for it about 10 years ago, and in that time I’ve not discovered a great deal about it!

Many thanks, Scott