British WWI Helmet with Painted Formation Insignia

British helmet has dark olive textured finish; sides have clear painted horizontal red line formation signs.  Interior has third pattern Brodies liner which lacks the felt crown pad, chinstrap is intact and pliable.  I had a look through Kevin Beckhurst's reference on formation signs which revealed that there are several candidates - at least five different units utilized this simple formation sign for identification.  $200 - $300