The Royal Family is German. Does that explain it?
The real answer is that the British government doesn't let them. It's a Constitutional Monarchy - except in certain very limited areas the Monarch and the Royal Family have to do what the elected government says.
The Foreign Office has been pro-Arab for decades. It isn't always anti-Israel (although at times it certainly is) but even when relationships are better than at others, not offending the Arabs is still the FOs priority above anything else.
Also there was Nazis in Royal family rumor has Edward VIII may have Nazism sympathy to Hitler
Also Prince Phil two of his brother in law were top officer in Hitler army
Then Elizabeth's dad, Bertie, took the throne as George VI. He was a good man. As World War II began, Bertie had to kick the brother and his consort out of the country to Bermuda for the duration, because, being active Nazi sympathizers, they were a big, fat security risk in London.
Since poor Prince Charles appears to be a greenie pinhead, I'm not quite shocked that he also finds anti-Semitism an easy reflex when it is fashionable. (And notice that Charles got entangled with a mystifying commoner divorcée as well. Not kosher for heirs to the throne, by tradition. What's the fascination, Charlie?)
The Foreign Office probably influences the Royals in this vein. Like our State Department, it has been seething with upper-class Arabist anti-Semites for a century.
Two reasons:
Too much inbreeding.
Ingrained British aristocratic anti-Semitism.
If it weren’t for their Jewish Prime/Foreign Minister Benjamin Disraeli, the UK would still be a small fishing country with bad beer and bad teeth. Well, one out of three isn’t bad considering that the British Lion has no teeth, and only one or two aircraft carriers.
>>The Royal Family is German. Does that explain it?<<
You sure about that? I think the royal family is Jewish.
Take a look:
http://kavkazcenter.com/eng/content/2013/06/28/17989.shtml
http://northerntruthseeker.blogspot.com/2012/12/the-truth-about-so-called-british-royal.html