Household Cavalry's Blues and Royals regiment
Harry, however, does have a strong affiliation with the Queen's armed forces. He served in the army for ten years, was twice deployed to Afghanistan and continues to support servicemen and women; he set up the Invictus Games in 2014 specifically to help injured personnel.
It's likely, therefore, that he will opt for a military uniform, rather than a suit, on his big day. Historical advisor Alastair Bruce said: "If he wears a uniform it would probably be that of captain in the Blues and Royals, part of the Household Cavalry Regiment, which was his uniform while serving. With this, he often selects the Army Air Corps light blue beret because he was an Apache helicopter pilot, memorably during his service in Afghanistan."
He added: "The Duke of Cambridge wore the uniform of the Colonel, Irish Guards, because he had recently been appointed to this by the Queen and his wedding, as a future monarch, was a ceremonial one."
The navy blue uniform features gold wire shoulder cords, ornamental gold braiding and red and gold cuffs.