FEBravo Cameron and Osbourne came in post financial crisis under the guise financial competence and immediately brought in a period of austerity. This wasn't pleasant but it also wasn't controversial to the general public at the time because quite a few countries in Europe, including Germany were doing the same. But considering that borrowing costs were at generational lows at the time, the decision was a poor one. Meanwhile the US went a different path and the divergent fortunes between Europe and the US can be explained largely by their response to the GFC.
So why single out Cameron? Well, most countries in Europe ended their period of austerity in 2-3 years (unless you were Greece and had a gun to your head). Meanwhile the Tories willingly continued austerity policies till 2019 and over this time every single thing the government touched was hollowed out. I used to work with an NHS foundation trust between 2013 and 2016 so had fairly detailed access to their finances at the time and year on year I could see how unreasonable the expectations were. There was definitely fat to trim at the start but by 2016 austerity was punitive and ideological. This was repeated across every public institution and, because nothing broke during Cameron's watch, he largely got away with it but make no mistake the reason nothing seems to work today is because of the decisions that were made during his watch. By the time Covid came around, there was no contingency or surplus that councils, hospitals etc could tap into and we're now paying the price (at a higher cost of borrowing!) to reverse those changes. Even worse, public finances did not meaningfully change between 2010-2019 anyway.
It may not have been the primary reason but one of the reasons Boris Johnson won the 'Red Wall' was precisely because he promised to turn on the spending taps once he was elected and, to be fair, his first budget was a dramatic increase in spending - although Covid had other plans in the end. Speaking of Boris Johnson and everything that followed, I blame Cameron for that too. He was the first to put party over country rather than face up to dissenters. The purge following the Brexit vote meant that any competent person that voted Remain was seen as tainted and were pushed to the backbench. Since 2016, it's been essentially a government in absence because so much energy was focused on Brexit and Covid that nothing else happened. There's genuinely no competent people left which is why Sunak is now putting together the worst campaign ever because there's absolutely no adults in the room. I have no opinion on Starmer because he's not given me a reason to have an opinion but the base is genuinely so low for him that even if Labour tackle some of the low hanging fruit in a competent manner, things could just become that little more pleasant.
Did the Tories do anything right? I was a bit flippant responding to @Burnwinter as I still believe that on balance they've comfortably a net negative over the past 14 years but they've overseen some wins. For one, they oversaw a dramatic reduction in coal use from 30% to 1% and made the UK one of the largest markets for offshore wind in the world, increasing the minimum wage above inflation, addressed pensioner poverty, managing to keep unemployment relatively low and a few bits and bobs. In general the kindest thing I can say about the Tories is that they aren't as bat shit as the Republicans but I fear that they will rapidly move in that direction after this election in the interest of self preservation. Frankly, I don't think they have a choice if they want to survive.