Tudor black bay bronze

[Broussard]

Aluminium Bronze will still darken, but not to the same extent and not as Brownish as the usual CuSn8 Bronze used in watches (Copper & Tin)

Exactly.

Using an aluminium bronze seems an odd choice, especially if you want to "guarantee the development of a subtle and unique patina." Perhaps "subtle" is the key word here.

Still no word on the exact nature of the new movement (or indeed old movement). Last year, a very eminent Rolex expert reported that the movement was assembled, but not entirely manufactured, in-house.

ETA: the expert has been offered a visit and can confirm it's all now in-house.