None of us have reliable information about the conclusions of "all academic historians" who have carried out work in the Great War have reached (insofar as "reaching conclusions" in this sense is what historians in general do, which is questionable.)

I think Keith misunderstands what historical study consists of, and how much weight can be placed on the judgements historians may make at any specific time. Speculation is speculation, and is by definition subjective, whoever makes it.

Basically the relevant distinction is the same as that once made of good newspapers - "opinion is free, but facts are sacred". The facts assembled by historians are where we should be willing to defer (provisionally). The opinions are essentially just that, opinions.

There were several million British soldiers, and the suggestion that all of them were or were not dupes, or did or did not understand what was going on is a meaningless generalisation, whoever might make it, songwriter or historian. The most that can be said of such matters is that it can be proved that some of them held a particular opinion, on the basis of what they might have written or said. The only generalisation that can be made is that they had a very hard time of it and that they deserve our respect.