Not everyone buys only new cars. Besides, in a world in which research was not censored, do you really expect that VW would have been slower to fix the issue?
No but I don't think they would of been faster either was my point.
Hence, to answer to the question posed "So how many vulnerable cars are on the roads of the world right now because the UK High Court wanted to "protect consumers""
I would answer 'possibly zero, BECAUSE of that' and once they are manufactured and sold they exist regardless of the owner, till they are destroyed.