When Amazon delivers a £20 book to a lady in Cambridge, how much of that is UK profit? The brand, marketing, procurement, software development, author mindshar

When Amazon delivers a £20 book to a lady in Cambridge, how much of that is UK profit? The brand, marketing, procurement, software development, author mindshare, etc. etc. all originate (if not implemented and housed in their entirety) in Seattle. 50%? 10% 1%? Who decides? At the moment, it seems like the answer to that is: each company involved makes some kind of judgment as to what amount of tax paid will get the local authorities, committees, and press off their back.