Today the Royal Marines took up guard duties at Buckingham Palace and other locations around London to celebrate the 350th anniversary of their creation. The last time they guarded the palace was in 1986. Far more often, units of the British Army and Royal Air Force take up guard duties and, on occasion, military and police groups from Commonwealth nations also take part.
However, I have always wondered why the Royal Navy has never participating in guarding royal residences. I think I may have found the reason and like so many other strange things in the world of state ceremony, it comes from a few odd quirks in history.
Judges, magistrates and members of the armed forces in the UK still take an oath of allegiance to the sovereign. But the Royal Navy does not require an oath as it was established long ago by “sovereign’s prerogative.” I am guessing this means their allegiance need not be questioned but it also means it is not as explicitly stated as the other branches of the armed forces. While it may sound ridiculous, the reason the Royal Navy does not guard Buckingham Palace may be that they do not swear an oath to guard the sovereign in the same way as the other branches.