This must be a joke, right?
BoJo was literately taken down for partying with colleagues during the lock-down mandates, Sunak was there too. And to be honest, I don't think sobriety is even the Anglo-Saxon lexicon; they're regarded as the worst tourists in Europe because of their rampant and belligerent alcoholism: they're only slightly behind the Russians in that regard.
Brexit was inevitable, they were never really an EU state in anything but name: they had the strongest currency which they were never going to give up, no Schengen agreement but benefited from it as well as the free-trade zones and cheap labour policies from mainland Europe that created lots of resentment--lots of Polish, Czech workers refused to go back during the massive shortages (truckers, nurses) during COVID because of how they were treated in the run up to Brexit. Ultimately the UK suffers from a very insular Island mentality that makes it questionable if they're even European at all--by contrast I think Wales, Ireland and Scotland are definitely European cultures.
Look at my recent post history, I'm not exactly an Anglophile but I've lived and worked in the UK and spent lots of time immersed in the many sub-cultures of the UK one of the reasons it's odd culture appeals so much to me is that it's likely the only modern analogue of the US and it's foreshadowing the fate of the US if things don't get corrected.
It's a cautionary tale and it's political upheaval and overall decay in influence and subsequent loss of both soft/strong power is worth studying. There was nothing slow about it;s decline, after the end of WWII it was apparent and obvious to see the sun had set on Britannia and it went to it's Pirate roots and served as a money-laundering hub for the elite and corrupt: there is a reason why it was called Londongrad by Russian oligarchs.
Adam Curtis is really good at detailing how it happened, Bitter Lake and Hypernormalization is a good start.