Fun fact - leaded petrol isn't actually banned in the UK, you can legally buy it and use it. The legislation at the time of bans just made it so that leaded petrol could only be a small % of overall petrol sales by any given fuel station, arguing that it allowed time for owners of unleaded-incompatible cars to purchase it.

And....it worked pretty much exactly as designed - initially only the largest stations carried it because they could justify the storage costs, and eventually it disappeared from almost everywhere. Just before covid there were still 3 small garages selling leaded petrol by the drum, but afaik they all stopped doing so.

And regardless - you can stil buy actual real Tetraethyl Lead fuel additive which turns your petrol into actual real 4-star leaded petrol, just like in the old days:

https://www.demon-tweeks.com/tetraboost-e-guard-15-fuel-addi...

I recall there's one factory on the planet still producing TEL, so once they decide it's no longer profitable it's over.

Aviation gasoline is probably the one market that still keeps it afloat, when/if piston aviation switches over the remaining market is small and insignificant.