When I was at school the ‘air’ way was definitely the standard, including a couple of Aarons in the class but the US/Aus ‘ahrr’ way seems the default now. Not sure if it was just a North London crappy way of saying it or cultural hegemony has changed things. English people seem to more commonly say ‘Nike’ as ‘nikey’ now (which is obviously correct going with the Greek etc.) but I think it was always just rhymed with Mike as a kid. (But then we all said Nestlé as nesslay because the adverts did whereas my mum grew up calling it Nestles and I think adverts in her day said it like that too.)