As I said I was being a little provocative. However since it seems to have yanked your chain, the case is made in this fashion.
Firstly the figure you offer for Mao is excessive, the best estimates I have encountered rarely put the figure for Mao in excess of 35 million, but there is no certainty of more than 18 million.
Gallipoli 1/4 million.
He was a senior figure in the war cabinet, as first lord of the admiralty, and also fought on the battlefront after resigning his post.
Churchill was one of the main instigators of Allied intervention in the Russian Civil War, perpetuating the conflict, he also blocked aid, the war cost 8 million lives. It also crashed the Russian economy resulting in 6 million further deaths from famine.
Churchill helped arm the Polish in their invasion of the Ukraine, supported the black and tans in the Irish war of independence, and pushed for the Kurdish uprising to be gassed, and lobbied for Burma oil (now BP) to have exclusive rights to Iranian oil, for which we are still paying in lives.
Churchill beligerancy during the general strike and his economic policies as chancellor have been argued to have increased poverty significantly and may have been responsible for 1/4 million extra deaths.
Churchill opposition to Ghandi, and Indian independence has been argued to have cost 5 million lives in the violence of the Raj towards non violent protest.
Once Churchill was in place as prime minister in WWII it's long been established that the government was aware of the concentration camps in Germany and subsequently the Death camps, and decided to do nothing directly. There was also the policy of not following up on Bletchley Park's knowledge of U Boat movements. And as an allied leader bares some responsibility for the other 40 million who died in WWII.
Then there is the Bengali famine in which he directly ordered grain held in store not be released, sacrificing Indian Lives for supposed future British need. About 5 million died, Your offered perspective seems to me to be somewhat Euro centric on this issue.
Now:I agree it is arguable, but as the above shows the case can be made.
Churchill was a great war leader, but he was also an obnoxious belligerant borderline fascist who endorsed eugenics, to whom a great number of deaths can be attributed, either directly or indirectly.
And the numbers match quite well with the substantiated claims for Mao.