In 1918, Tsar Nicholas II and Tsarina Alexandra along with their 5 children were murdered by the Communists. It has been well established that the order to kill the entire family came from Lenin. Prince Philip is the descendant of Alexandra's oldest sister, Victoria. While this is an exaggeration (half of his family wasn't killed) I don't think it is a slip up. I can certainly understand his being upset with the Communists.
This 'comment' was a collection in a publication my mum sent me from England and according to the book, Prince Philip "blurted out" this rather rude comment in a roomful of press agents. Yes, he has every right to his opinion but as we all know, the Royal Family are supposed to act in a somewhat dignified manner. If he wanted to vent his anger at the Russians, there are many other less foul words he could have used. British people, who pay his salary by the way, are sick and tired of hearing smut and rubbish fly out of this man's mouth. Prince Philip often uses the excuse after one of his obnoxious quotes, "It was just a slip of the tongue." So there you have it! Straight from the horses mouth!
Yes of course, he has a right to be upset with the communists. But, as a statesman, he should know when to shut up. He probably would have shown to be a great man if he tried to make the world better. If too difficult, a plain «No I won't go», would have sufficed.