This is very sad news. I was hoping that Sir John would make his century but 98 is a fine age.
Mills was one of my favourite actors and very under-valued. The role call of great movies listed above is hugely impressive (and it doesn't even include my personal favourited, THE OCTOBER MAN and GREAT EXPECTATIONS).
Just last night I was enjoying his turn as the seedy private investigator in END OF THE AFFAIR, a good example of his veristility.
My thoughts go out to his friends and family.