Ed, we concentrated on military through Dress Regulations, Army Council Instructions and impeccable sources like Brian Davis, Ron Kidd, John Mollo, Michael Barthorp etc (see the Bibliography). Civilian hats/helmets were used e.g. Cawnpores and the Bombay Bowlers but we found no official presence for them. That is, apart from the Cawnpore's use being discontinued by ACI 284. There is no doubt that officers bought civilian helmets but issue to the men is problemmatic in the early days. However, following is a photo showing soldiers waiting to embark and either wearing Cawnpores or wearing the Colonial pattern helmet with a Cawnpore strung across their backs, or vice versa. So it may have been a regimental issue of civilian helmets to preserve the regulation cork one. The Indian authorities, generally speaking, did not appreciate the cost of cork helmets and were always looking for ways to get around the War Office edicts and therefore save on expenditure. Stuart PS. Can't do any better on the resolution of the photo.