Being the sole western industrialized nation that hadn't just had most of their infrastructure bombed to rubble can't have hurt.
Last time I checked, WWII ended 80 years ago.
This was quite robust until <group that disagrees with my political opinions> screwed it up for ideological reasons (fortunately, I guess, I can say this in a non-partisan manner because everybody thinks the other side blew it. My side is correct, though, of course).
What isn't a myth is the billions of dollars given to them. The same billions were given to Japan and Korea and they actually used it to bootstrap an advanced, sustainable technology-driven economy. Europe squandered the opportunity.
The article mentions but underrates the fact that post-war the British shot themselves in the foot economically.
As far as I'm aware, the article is kind of wrong that there wasn't a successful British computing industry post war, or at least it's not obvious that it's eventual failure has much to do with differences in basic research structure. There was a successful British computing industry at first, and it failed a few decades later.
If the main failure of British companies is that they don't have U.S. company market caps, it seems more off base to blame this on government science funding policy instead of something else. In almost every part of the economy, U.S. companies are going to be larger.