Think of it in terms of a retail distribution network.
You will need a warehouse (data warehouse) where all the products (information) is collected and kept
You will need a store (data mart) where you can provide a limited number of products (infomation) to your customers (users).
I would push for a single enterprise wide data warehouse, but provide a materialized data mart (i.e. not dynamic views) for each user class - these classes may be geographical (UK, US, CN) functional (Finance, HR, Marketing) or level (operations, management, City reporting) and any combination of the above.
The actual technology stack needs an architect but the design principles would remain the same. I know that personally we are having real problems getting our US company to release data for storage outside the US for legal issues (federal and commercial).