And just how bad is Wendy Morton?
More to the point, who is she?
(Sorry - I see this has been answered above)
Someone's got his true-blue spectacles on. Cameron quit because of his failure to win the Brexit referendum, and his reputation has not been helped by the Greensill scandal. Brown was well-regarded as Chancellor but lost as PM because of the economic crash.
Thatcher and Cameron, of course, both prematurely ended their own careers by their own actions. In the case of Thatcher, she may not have survived much longer anyway, but Cameron quite dramatically and stupidly cut short his time as PM.
Thatcher because she thought that she could do anything and large sections of the electorate would still love her, Cameron because he was too weak and frightened of Farage.
If Thatcher had not implemented the poll tax, she would probably have remained prime minister, but maybe only for another 18 months as I suspect, with Thatcherism profoundly unfashionable in the early 90s, she would have lost the 1992 election. The early 90s recession would of course still have happened if Thatcher was PM in 1991, and her likely lack of sympathy for those falling on hard times as a result would have finished her off in 1992 I suspect.
If Cameron had not called for the referendum, he would have remained PM until 2020, and perhaps still be PM now. The 2020 result would rather have depended on who his Labour opponent was: I suspect he could have won again versus Corbyn, but lost to another Labour leader. Cameron, and May, are perhaps the two most profoundly politically naive leaders of modern (Thatcher onwards) times.