The shoulder line is key on a bespoke suit. Once you have a strong understanding of that, the rest flows from there. ~Ozwald Boateng
According to AW London / Savile Row, there are three British shoulder construction standards:
A Classic British Suit – The Shoulder
1. The shoulders should neither be too narrow or to wide, but slightly hug the shoulder
2. Shoulders should be padded to add structure, rather than bulk
3. There should be a sharp 90 degree right angle between the shoulder and the sleeve of the suit
British tailors have historically used just enough padding to follow the natural shoulder line, with a precision fit that could be suited for the military. Some tailors will barely extend the natural shoulder line so that the sleeve will hang straighter.