Upvote:3
It has been claimed that this general was Sir Launcelot Edward Kiggell (1862-1954), but there seems to be a lack of evidence. Kiggell was Chief of Staff to Douglas Haig, and another of Haig's staff officers, John Humphrey Davidson apparently claimed that it was himself.
The descriptions I've read of the conditions at Passchendaele make it seem plausible that several generals might have said something like this.