Harry Mount is a British journalist and author. He is the current editor of The Oldie Magazine. The opinions in this article belong to the author.

(CNN) It shouldn't be that surprising that Prince Philip is retiring from royal duties, as Buckingham Palace has announced. After all, he's 96 -- 30 years older than retirement age for most of us.

In fact, here in Britain, news of his retirement hit us like a bombshell. Like his wife, Prince Philip looked like he'd just go motoring on forever.

That's partly the nature of monarchy. The royal family becomes the eternal background to your life -- particularly if, like the Queen, the monarch has been on the throne for 65 years, longer than most Britons have been alive.

It's also because Prince Philip is so extraordinarily fit and energetic. I met him 20 months ago at lunch, at the Cavalry and Guards Club on Piccadilly in London. I was blown away by his youthfulness and mischievous wit.

The lunch was for the Gallipoli Association, to commemorate the centenary of the doomed Gallipoli campaign in 1915 -- when Winston Churchill tried, and disastrously failed, to win the First World War by sending Allied troops up the Dardanelles.

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