SA, the whole “lockdown versus no lockdown” is a distracting oversimplification. It’s so obvious that it shouldn’t need stating, but it’s social behaviour that affects the cross-infection rate, not the law. Sweden couldn’t have a lockdown without a change in its constitution because the government is not permitted to restrict the population in peacetime, but “recommendations” from Sweden’s independent but official departments are treated by the population as if they were law, and social mixing has dropped immensely in Sweden.
Sweden has done better than the UK, probably because the Swedish authorities acted sooner and have given consistent messages throughout, and because the people have more trust in what their official institutions ask of them.