IMOO it would be wise for if any Royal or person of importance to change their method/type of travel frequently. This way it makes it more difficult for those wanting to do harm. Since the media reports on every little thing and the public wants to know every little thing about the Royals, they need to be extra careful. Just because the Royals travel with protection does not mean that method of travel is safer for them or the public anymore. Unfortunately it is the era we live in.