If he decides to run instead of Thatcher in '75, does he still beat Heath? If so, what will his premiership look like?
I'm sure butterflies can prevent that, or at least mitigate it. He wasn't personally responsible for a bank failure. So, let's butterfly said bank failure and he decides to stand. Advantage is that he's better known than Thatcher and Hugh Fraser's candidacy is butterflied, dunno about Howe's. As 1922 Chairman he's a very familiar face to backbenchers, probably a mentor to a few freshmen/sophomores as well. Certainly he'd have better PMQs than Thatcher did against both Wilson and Callaghan (or with butterflies, potentially Foot).
OK then: 2 butterflies. First no bank failure, second someone convinces him to PAY THE BLOODY BILLS. Strictly speaking, I'm curious about how far he would go as opposed to Thatcher as PM. Potentially backstabbing Howe in '81 when the wets start squealing.