Firstly Powell wasn't the youngest brigadier in the British Army in WW2, he was 31 or 32 before he was promoted to that rank , while Mike Carver who commanded 4 Armoured Brigade from Normandy onwards was 29 when promoted . Secondly unlike Carver , Powell never commanded a brigade or any other unit or formation. I shouldn't have written brigadier earlier , I should have written brigade commander. What is true is that Enoch Powell And Fitzroy Maclean were the only men to go from private to brigadier in WW2.
Only Wullie managed Private to Brigadier via all the ranks and went on to Field Marshal I think.