I don’t know that you can objectively measure such things as how “vehemently disliked” a prime minister was. Earlier PMs have the advantage of not having lived in a media age. A lot of the vitriol directed at Thatcher was just because people knew it was safe to target her. Call it the Ben Elton effect. A caricature of a PM becomes established, and people just copy it. Thatcher: evil dominatrix. Major: grey, anal retentive. Blair: insincere spin merchant. But they’re just caricatures, and tell you little about the real person.
Well then the UK would be headed by a woman in her 80s with dementia.