There is no reason why we should not have Trooping the Colour even without a monarchy. If you look at the history of it, it was because many of the soldiers were foreign and had to be made conversant with the flag they were fighting under. Consequently the flag was 'trooped' up and down the rows of soldiers so that they would know it before they went into battle. Not required now, of course, with modern day battles. Nothing whatever to do with the monarchy. I do like it though, and when my husband was alive we could not miss it. It is certainly a remarkable sight.