It had nothing to do with economics.

He was not "dazzled by collectist economics" in any way. If he had been he would not have been a Tory.

It was based upon the common, widespread (at least pretty much everywhere in the world outside the United States, apparently) philosophical belief that Mankind's great advances in medical science and medical treatment should be accessible to all, every man, woman, and child, regardless of position in life. Churchill himself drew the analogy to firemen. No matter if the structure on fire is the humbliest cottage, or the most luxurious mansion estate, the firemen will come and courageously battle the flames, put out the fire, and save all persons they can from the disaster. It is for the greater good of society that the firemen will battle every fire, not just those buildings whose wners have the means to pay for the service.

Likewise, every citizen and legal resident of the nation has a fundamental right to basic, and preventive, medical care. To pretty much everyone outside of American conservatives this belief is just obvious common sense , as serving the common good of society, as the right of every person to have the local fire brigade come and assist when their home is on fire. And of course, those who have the means should certainly have the right to purchase a higher level of medical service, either personally or through their employers or former employers.