There are, broadly speaking, two ways of measuring (get it?) greatness in tailoring. The first is obvious: the aesthetic, or line, cut, drape, and how a tailor’s ‘rock of eye’ is able to shape 2D cloth into 3D structure. The second is rarer, and altogether more telling: whose trust you have earned. In these terms, royal warrants are not merely decorative crests but a form of peer review, both contemporary and historical. A monarch, after all, has no shortage of choice.