I think it was the Parliament that did it. He went along because he wanted to stay PM but his heart was not in war. He stayed in office by doing what the majority wanted but just barely. As little as possible. That was the ‘phony war’ I guess.
There were even then still plenty in The Conservative Party that wanted no part of war. Even when Churchill took over, he was under constant threat of removal by his own party.
There is a great discussion on “The Phony War” in Ernest May’s “Strange Victory.” The French military leadership pretty much expected that with the British Naval blockade, they could sit it out behind the Maginot Line and Hitler’s Germany would just dry up and blow away without any real fighting.
I will post excerpts from that book during the coming months. Probably start in a day or two as we see the French “strategy” unfold.