British WWI Hood Battalion Helmet with Painted Formation Insignia

British helmet has dark patina and traces of dark olive finish; sides have faint but legible painted formation signs that appear to be a rectangle divided into thirds: green, black (or dark blue) and green.  Interior is similarly rough with a very well-worn second pattern liner and a replacement black rubberized fabric chinstrap that is now quite inflexible.  I had a look through Kevin Beckhurst's reference on formation signs and did not locate this one, but am thoroughly convinced that it is original to the helmet.  $100 - $150