HI Newbe
Is it possible to see a picture of the inside of the helmet. I have recently sold my complete British officers lance cap and yeomanry metal helmets through M.D.Long militaria. Just that while I was collecting I was offered a few of these helmets that I had doubts about all in mint condition, and with the same feather configuration as yours. I had all the line and yeomanry caps I fact three of my metal helmets are still on his site all officers yeomanry, not saying there is anything wrong with yours but the East Riding is the one they are doing at the moment.
thanks
Tony