I completely agree on the classism point, he was in a different position to my grandad who was a working class man who never had anything. He didn't have to hold his tongue because I guess most people around him at the time were the same. Prince Philip was different, you are right.Your Grandad wasn't married to the head of state though (well I assume not anyway...) nor was he a public figure.
Even with everything you have said there it doesn't excuse the classism.
I dunno, maybe I don't feel the same because my grandparents were mixed (as in one white, one black) so it would have been quite the scandal back then so the lazy/old school racism was never present in my past so it properly irks me when people like Prince Phillip say what they do.
It does worry me that I have seen so many people today saying that he was great because he "spoke his mind". Maybe he shouldn't have so often.
You are also completely correct in that I shouldn't try and justify either situation as "that's the way it was". The only way we grow out of this and learn is by stopping making excuses for what went before.
On the final point I guess I feel like my grandad wasn't speaking his mind when he said those things later in life. It was lazy old school racism and when we corrected him he realised. Whereas Prince Philip probably was speaking his mind. And that is not something to laud