An article in the Independent, quote political analyst James Kanagasooriam on this matter, the first monumental sandcastle was Boris Johnson's "red wall".

https://www.independent.co.uk/voices/keir-starmer-poll-sunak-labour-tories-election-b2563201.html

of course he's right ,but perhaps for rather shallow reasons. There won't be one "next big wave", but there's a whole tsunami of waves building up off the shores of the British Isles, global warming, overpopulation, immigration, the decaying economy and mountainous borrowing, , the fraying society and gross inequality, the decaying politics, the wars in Ukraine and the Middle East, the decaying of the US, and the arising of a multipolar world that Starmer and Labour in their imperialistic support of NATO etc, have yet to understand. And more importantly that the whole of the citizenry of the UK has yet to understand, and remain totally unprepared for.

Indeed the sandcastle will not last long.