SingingLily I agree with you about May. I think she got caught up with her fantasy as a Thatcher figure who would battle with the EU and come out with a good deal and lead the country into the sunset. In reality she was cloth-eared, never listening to anyone and a one note politician.. She completely got sidetracked by Brexit and hadn't got the influencing or political skills to deliver that either. Thus leaving the way for the ERG to take over.
I'm not sure about conviction politicians though. They can be dangerous because they never question themselves. Hence us having one of the only water and sewage systems that's privately owned (largely by overseas companies), is pretty expensive and still has a huge number of leaks and under-investment.
My sister had a problem with her pipes and five different Thames Water teams turned out before they sorted it, and according to Greenwich University, it costs consumers £2.3 billion more a year than if it was publicly owned. So while some privatisation of companies where competition was feasible, like airlines, was positive, it hasn't worked well in other areas. But because Thatcher was a conviction politician, she wouldn't see anything other than her vision of the economy.
Meanwhile Tony Blair took us into the Iraq war because of his conviction that it was the right thing to do. And Michael Gove was convinced that he needed to overhaul our education and examination system based on his own experiences at grammar school with no reference to experts. Cos what do they know? 
But if you're saying we need more politicians who aren't career politicians, who've come from business and industry, yes I agree with that. But not journalism because they tend to believe in their own scribblings, particularly those who write opinions pieces, enjoy being controversial for its own sake and like to stir things up.