I don't know about nowadays, but M&S used to categorise their shops as A, B and C.
I learned about this on a uni field trip to M&S years ago.
So A flagship stores were the central London ones, cities like Birmingham, Newcastle, Glasgow and Belfast had B flagship stores and the shops in provincial towns and suburban shopping centres were C stores.
The best items, including the best finished ones and with the best fabrics, and those made in certain factories, went to the A stores, the good but not best ones went to the B stores and the least well made ones to the rest of the stores.
I hope that's not still the case.