I’m not an epidemiologist, so I’m going out on a limb with this, but:

Looking at the infection rate curve, I think the lockdown was working right up until the more-infectious strain took over.

(“People tested positive” graph: https://coronavirus.data.gov.uk/)

The critical issue is to ensure the health system is not overwhelmed, and that was achieved. Prolonging the agony is actually a result of unwillingness to extend hard lockdowns for 4+ straight months over whole countries - we keep lowering restrictions as soon as possible.

But sure, things might have definitely been faster if only we just let more people die.