Queen Elizabeth II is probably the most well-travelled monarch ever. She has been to 116 countries on official state visits as Queen, but not Greece. Why?

The Queen has travelled from the tiny island nation of Tuvalu in the Pacific, to Russia, China, Chile, Ghana, Australia and almost everywhere in between.

It is not completely true that the Queen has never been to Greece - she did go there at the invitation of King Paul, Prince Philip's cousin, in 1950, but that was before she became Queen.

He lives in London, still considers himself king, and has a close personal relationship with the Queen, according to Michael Binyon, foreign affairs

So it may seem surprising that she has never made the relatively short hop over to the birthplace of her husband, Philip, the Duke of Edinburgh.

Prince Philip is a "Greek prince," says royal historian Hugo Vickers, so it is an "interesting" omission.

The reason, he believes, is because of the fraught history of the monarchy in Greece, which affected Prince Philip's immediate family.

"Prince Philip doesn't like Greece, because they put his father [Prince Andrew] on trial, and he might have been executed," saysVickers.

"In 1922, they all had to flee." Prince Philip was a baby at the time and rarely returned.

specialist at The Times newspaper.

All of this has "made things difficult" says Vickers. But he also suspects the Queen may have never been invited by the Greek president to make a state visit.

Prince Philip did go to Athens to visit his mother before she moved to London in the 1960s - but he would travel on his own, says Vickers.

Israel is another notable omission from the Queen's list of state visits.

Security is a major factor in this case, but, says Binyon, the biggest problem is diplomatic sensitivity over visiting Jerusalem. Israel regards Jerusalem as the capital, but it is not recognised as such by Western nations, who base their embassies in Tel Aviv instead.