Free, at the point of delivery, yes. But if you look at one of your pay slips, pre-retirement, you will see a heading: 'N.I. Contributions, and for every pound deducted your employer paid in two.
I'm not knocking the NHS, goodness knows I have had more than my share from it, it's just that it's not free.
On another thread our American friends have explained that when everyone puts into the pot for a service they might, or might not, need, that's socialism, something that the majority abhor. So they continue to pay absurd rates of insurance for their health care, so that they are free of ideology.