The Prince of Liège, later known as King Albert II of Belgium, who abdicated in 2013, also attended the funeral. As far as I know, the Duke of Kent, Princess Astrid of Norway, and King Albert II are the only three dignitaries still alive who attended the funeral.
Here is a picture of then-Crown Prince Olav of Norway, later King Olav V, and his daughter Princess Astrid of Norway arriving for the funeral.