It has been known by certain different names over the years and Rifle Green is popular again. It was also known as Brunswick Green but as Brunswick made Rifles for the Light Div it was also known as Rifle Green.
Being from a regiment with colours we used to wind up our trg pln commander by answering any colour name apart from the one he wanted to hear. Yes he was RGJ!
Southern Railway used a very similar shade known as Malcanite green. It doesnt matter as it fades with washing!