Today is a bittersweet day for the Duke of Kent as it is the 80th anniversary of him inheriting the title Duke of Kent. Of course he only inherited that title, aged 6, because today is the 80th anniversary of the death of his father.
I am not 100% sure but from my research I haven't found any other English/British peer who has held their title for as long as The Duke of Kent. I will stand corrected of course if someone is able to show me a peer who has been a peer of England or Britain for longer than The Duke of Kent (I say England or Britain because the title Duke of Kent has only ever been created in the peerage of those two entities).
I am sure that The Duke and his sister will remember that day with a lot of sadness. I didn't include Prince Michael as he was only 6-7 weeks old and so would have no memory of his father at all.