I don't think you can tell this story starting that late tbh - you have to go back to the early 90s and the Eurosceptic wing of the Tory party leaving pro-EU John Major out in the cold with no support as the sleaze scandals closed the walls in on the party.
Labour should have won in '92, but Neil Kinnock managed to commit the worst political crime possible in the eyes of the British - overconfidence. Major managed to cling on and for 5 years we had an absolute shambles of a Tory government during my early teenage years that Labour would've easily toppled at any point either with John Smith or Blair once Smith died.
Labour spent that 5 years dragging their image out of the strikes of the 70s/80s eventually into the same free market optimism as Clinton leant on in the US - Thatcher once described Tony Blair as her "greatest achievement" - although the Tories were out, "small c" conservatives were still running the show and for all Gordon Browns best efforts at rounding the edges they largely followed Thatcherism for 10 years until the Credit Crisis hit in 2007.
That's when everything really blew up.
With conservative economics on the ropes people knew we needed an alternative - but what was available? Labour were essentially Tory-lite by that point, the actual Tories were still bouncing from leader to leader and so the Lib Dems decided to try and convince the nation they were now the "lefties" who could tug Labour back into shape.
The Tories realised their only option was to blame anything but conservative economics for the problems and hope the public bought it. Blame the "Labour Government" despite the credit crisis being a global phenomenon, blame the EU despite other members not being as badly affected as Britain, dog-whistle every conspiracy and when all the economic heavyweights of the day were calling for windfall taxes and public spending, call for Austerity more extreme than we'd ever seen in peacetime. By and large, people bought into their shyt all over the country.
The resulting election tore us apart and we've only drifted further since. Rather than Labour being forced into Coalition with the Lib Dems in some sort of Left/Liberal fantasy land, we got a Tory/Lib Dem coalition, Labour in tatters and promptly found out that the Lib Dems didn't actually give two flying fukks about left-leaning economics after all. Once they were propping up David Cameron's government, they dropped nearly all of their campaign points just so they could have some jobs in cabinet for a few years.
In the meantime, the Tory party hadn't solved a single thing about the EU split that had been pulling them apart since the 70s - Cameron could see the 90s chaos returning and in an effort to get his own party behind him, he started campaigning for a Brexit Referendum (although as a Remainer).
Instead of exorcising the issue once and for all, all it did was bring it to the surface forever more. The vote was held. We left the EU. The Tory party is still split down the middle, but the country is now weaker and economic issues are now amplified. The Tories have been trying to find a "unity leader" ever since, but every member knows that there is only "them and us" - whoever they install, half of the party will hate them. They tried May, they tried Boris, they've tried Liz... none of them worked, because the Tory party doesn't work.
I think it's possible if David Milliband had been elected we could've avoided the whole thing, but I doubt it. Ed was brought down by the media machine leaning on stories about his Communist Dad - also David's Dad - neither of them would've been allowed near No10. Same tricks used with the full force of Internet viral conspiracies against Jeremy Corbyn made sure Labour offered no real challenge until the handling of COVID had shown the public that the Tories weren't just unpleasant, they were downright fukking dangerous.
Labour will get in now, because the country has no option. It's just a shame what we're going to get is conservative Labour again.
to you sir.
Skulking off to a shed won't cut it
