She did after all come in a reasonably close second to Michael Foot (56.5-43.5) in the 1976 Labour Deputy Leadership contest. https://en.wikipedia.org/wiki/1976_Labour_Party_deputy_leadership_election If she had won it, and If Callaghan wins the next General Election (as some here have speculated he might have done had he called the election in 1978 instead of 1979) and she retains the seat she lost in OTL in 1979, could she be Callaghan's successor as Prime Minister? ( I assume that in this scenario Labour doesn't move nearly as far to the left as it did in OTL and the SDP secession from the party never happens.) In that event, she rather than Margaret Thatcher would be the first woman Prime Minister of the UK.
(Yes, this post was occasioned by her recent death.)
(Yes, this post was occasioned by her recent death.)