As alway, all this has been covered by Jonathan Lynn 20 years ago.
"Things don't happen just because Prime Ministers are keen on them. Neville Chamberlain was keen on peace."
The reason for going to war?
"The problem of the Ministry of Defence is that in peace time the three armed forces have no one on whom to vent their warlike instincts except the cabinet or each other."
The reason no one stopped the war?
"In government, many people have the power to stop things happening but almost nobody has the power to make things happen. The system has the engine of a lawn mower and the brakes of a Rolls Royce."
The reason MPs always get it wrong:
"Being an MP is a vast subsidized ego-trip. It's a job that needs no qualifications, it has no compulsory hours of work, no performance standards, and provides a warm room, a telephone and subsidized meals to a bunch of self-important windbags and busybodies who suddenly find people taking them seriously because they've go the letters 'MP' after the their name."
Make up your own mind on these:
"There was nothing wrong with appeasement. All that World War Two achieved after six years was to leave Eastern Europe under a Communist dictatorship instead of a Fascist dictatorship. That's what comes of not listening to the Foreign Office."
"Britain should always be on the side of law and justice, so long as we don't allow it to affect our foreign policy."
"Press statements are not delivered under oath."
"The Foreign Office aren't there to do things. They're there to explain why things can't be done."
"People have said a lot of unpleasant things about the Foreign Office, but no one has ever accused them of patriotism."