He loses some marks for his threat to retire when offered Twelfth Army.
Well, that was an insult, and Leese should never have offered that command to him. He told Slim to his face that he was unqualified to plan or command Operation Zipper, the assault into Malaya, offered the 12th Army command to him (basically going from command of 14th Army to just 2-3 divisions) and then gave the 14th Army (or tried to at least) to Christieson without clearing it with Brooke, who tore him a new one when he found out.
Slim was convinced that he had been sacked, that Leese had the right to do so, and that he would rather retire than command 12th Army. He had just carried out the masterstroke of Operation Extended Capital, which
obliterated the Japanese in Burma, and that somehow didn't count?