They don't work regardless of when deployed. The idea the UK was late is doing the rounds inside the UK establishment but it's wrong. If they worked places that stopped doing lockdowns would have seen huge surges and higher death rates than places that kept them, but that didn't happen and there are by now many such examples. Lockdowns don't work because (a) COVID doesn't seem to care about them and (b) COVID is nowhere near deadly enough to justify them, as demonstrated by the counter-example states and countries that rejected them and saw far less than the predicted mortality.

> The idea the UK was late is doing the rounds inside the UK establishment but it's wrong.

You seem frankly a bit divorced from reality. If you go to a chart of the daily incidence rate before either the first or the second wave, then mark on it when the lockdowns occurred, it's clearly visible that they occurred too late.

I had to discourage my at-risk mother from going to a choral Christmas concert last year, at a time when they were clocking 40,000 new cases every day and that number was doubling every few days. That chart is etched into my brain because of how worried I was, and at the time, conservative ministers were still going on TV and talking about a five day christmas.

If you go to the deaths graph, you can see that as a result of this awful mistake, tens of thousands of people died. This is plainly visible in the statistics. Whatever political axe you have to grind is frankly irrelevant, and to be honest, facetious.

You seem to be trying to identify causation from a single graph. That's not how data analysis needs to be done. You have to compare different datasets that vary in the control variable. In the case of Europe the UK vs Sweden is a good comparison because they are similar in most ways that should affect viral propagation except for lockdowns. Sweden has seen significantly better death rates than the UK, despite the theory saying they should have done much worse, meaning the theory is wrong. Because the theory is wrong you can't derive anything by looking at UK curves in isolation and comparing them to a theoretical counterfactual.

You can also look at the different performance of US states (none) despite very different measures.

That chart is etched into my brain because of how worried I was

In other words you were terrified and forced that fear on your family, based on a mis-understanding of how to use data to draw scientific conclusions. And now you're accusing anyone who points out the truth to you of political axe grinding, although it's you who just threw in a random mention of "conservative ministers" implying their politics is responsible for lots of deaths. That's a political talking point!