Who was the british prime minister in1938?

Neville Chamberlain- he took over as Conservative Prime Minister the previous year, replacing Stanley Baldwin, and attempted to forestall another European war at the Munich Peace Summit in '38, when he and other major European leaders persuaded Hitler to sign a declaration agreeing not to expand the Reich into any further territory than it already had done. But Hitler broke his promise the following year and invaded Poland in early September '39, forcing Chamberlain to declare war on Germany on 3rd Sept.

He went on to send an enormous British taskforce numbering some 150,000 men to back up the French Army when German troops invaded France, but despite both the British and French inflicting heavy losses on the Nazis, they were pushed back to the West coast of France by the might of the advancing Panzer divisions. This led to the disastrous evacuations at Dunkirk and to Chamberlain's resignation in May 1940, when he was replaced by Winston Churchill.