You could also convert cars by putting harder valve seats in, not sure if this happened a lot at the time, or whether it’s more for classic cars that are worth enough to make sense to do. I don’t think the lead was primarily an anti knock additive, more of a valve and bore lubricant

The UK has something in common with Ireland that maybe the rest of that EU doesn’t perhaps?

I don’t really see how this represents any proof that these asylum seekers are illegal economic migrants. Rwanda isn’t a safe country for asylum seekers, so it seems reasonable that people would try and avoid being sent there. If Ireland now appears safer, then travelling there from the UK makes sense surely? The position for “illegal economic migrants” hasn’t changed substantially, as the likelihood of being sent to Rwanda is low. But if you are trying to reach safety, the threat of death or torture hanging over you might be enough to make you consider Ireland

Yes, the UK justice system works on the same principle