Oh! What a Lovely War!
That picture was released in 1969, but I find some people on-line insisting that this was the original title of "How I Won the War" 1967 (which doesn't make any sense at all since Patrick Ryan's book was so named and is kind of the punchline of the movie) and that John Lennon had a small part in the latter film.
One fellow on e-Bay is selling a lobby card for "Oh! What a Lovely War" and refers you to the internet to look up JOHN LENNON OH! WHAT A LOVELY WAR! and if you do, sure enough there are some comments, and even one site that sells photos and posters that is selling a black and white photo of Lennon dressed in his Private Gripweed outfit with the caption saying it is from "Oh! What a Lovely War!".
I know that Richard Lester's black comedy is a bit obscure and maybe that is the reason why there is rampant confusion. Or I am the one who is confused? Rampantly speaking.
Thanks in advance.