My post is about the use (or abuse) of will in a sentence beginning with "when".
In France, learners of English are constantly told that they must not use will after the conjunction "when" except in reported speech (as in "I'm sure you're wondering when this peroration will end"). I quickly browsed some recently published grammar books and I found this rule still maintained with an interesting caveat about the phrase "the day/time/moment when" which tolerates (or is it requires) the otherwise forbidden "will".
So you will understand my surprise when viewing the latest Stephen Frear's film ("Mrs Henderson presents") I heard the girls singing "when the war will be over and won". I then checked this phrase on google and realized that this looks like a set phrase/cliché (alternatively with "will" or with "is").
Any opinion about this?