Queen Elizabeth II and Prince Philip have been married for almost 69 years, and sometimes they look like they have dropped from a fairytale.

However, there is a catch. They have never displayed affection for each other publicly. Why doesn't the Duke of Edinburgh, who turned 95 on Friday, not hold the Queen's hand in public?

Right from the beginning, the couple has built up a solid marriage that has remained steadfast since 1947. At first the public was not too keen that their Princess should marry Prince Philip of Greece and Denmark, as they felt that he did not cut the ice. Still, the royal couple tied the knot, and have held together since then.

But in public, it seems to be hands off---unless the Prince holds out his hand to her during a walk.

Why not? Is there something wrong in holding hands? Do they feel embarrassed? Is there a remote possibility of their marriage being on the rocks?

Not in the least! "If we regard the Queen's record-breaking reign as a success - and I think most of us do - Prince Philip is the co-author of that success," royal biographer Giles Brandreth explained to Radio Times. "The Queen wears the crown, but her husband wears the trousers. He is the power behind the throne - shrewd, steadfast, never-failingly supportive."

It's only that Prince Philip believes in the age-old "stoic values". He is a "pragmatist" unlike his "romantic" son Prince Charles, explained royal biographer "I once asked Prince Philip about the reported differences between him and his eldest son, Prince Charles," Brandreth wrote. "He acknowledged 'one great difference' between them. 'He's a romantic,' he said, 'and I'm a pragmatist - that means we do see things differently.' He paused before adding, with a shrug, 'And because I don't see things as a romantic would, I'm unfeeling.'"

Strangely, their grandson, Prince William, also does not hold wife Kate Middleton's hand when they go out for official royal functions. Is he a pragmatist too?

Not really. The Duke and Duchess of Cambridge do exhibit "public display of affection," or PDA informally. However, they do not touch each other when they come out on official engagements.

Royal etiquette expert Myka Meier said that even though there has been no royal guidebook on PDA, Prince William and Kate do not show it, because they happen to be representing Queen Elizbeth II.

"The likely reasoning is more that while travelling on a tour such as the India trip, technically the couple are working representatives of British Monarchy," she said. "The couple are likely to show very little PDA, if any, to remain professional during their designated roles abroad."

One thing they do have in common is---singing. The love for music was passed through the ages. You can listen to the King and Queen sing and decide whether they are involved in a love duet or not.