You could write them a letter and tell them that the UKMoD doesn't have any record (so far as their records go nowadays) of a Lee Enfield breaking due to water on the ammunition or the rifle. You could also say that Malaya had/still has its fair share of wet weather ......, in fact it has daily monsoons that you can set your wristwatch by. In fact, monsoons to end all monsoons, that would shove big armoured Bedford QL and RL trucks off the laterite tracks with their ferocity and the little Lee Enfields seem to have behaved admirably there.
Of course, I might have been missing something but I certainly didn't keep my rifle under a groundsheet or a poncho. Maybe the editor knows something we don't know. Maybe you could ask Chris White to contact me at the Small Arms School................................