I've had this helmet for many years but have not yet properly identified it. I assume the R is for Rescue but do not understand why is coloured white. I do not know what the two bars are under the R (marked front and rear). There is little to go on with inscriptions. All I can make out is 'VI' by the chinstrap lug. If there was anything else it is obliterated by rust. Can anyone shed any more light on this? Thank you.