Who Said This About Vietnam?

[BluffTHIS!]

Who said the below quote in 1938 after agreeing that Nazi Germany was entitled to invade the Sudetenland areas of Czechoslovakia in order to secure peace at any price at that moment, heedless of future consequences?

"My good friends, for the second time in our history, a British Prime Minister has returned from Germany bringing peace with honour. I believe it is peace for our time... Go home and get a nice quiet sleep."