Edmund Barton was Prime Minister from January 1901 to September 1903.
I'm guessing you mean Neville Chamberlain, who was British PM from 1937 to 1940, when he was succeded by Winston Churchill.
Arthur Meighen Prime Minister was the 9th Prime Minister of Canada.
If you mean in the UK, it was Tony Blair.
He was prime minister twice, his first time was on the 10 May 1940 and the second time was on the 26 October 1951