Either we're talking about something entirely different or you do know something I don't. Business rates?Yes I know what it is. I asked what rates are incurred by having a locked section of a warehouse that is bonded?
It's none BTW.
Plus not having to pay for parts you don't yet need (and might never need), staff to count them, cost of building or renting the warehouse.
The point of the post by "without a dream" that you commented on was that any customs delay in cross-border movements of parts threatens the reliability of the just-in-time system.
Brexit reality says this is a problem. https://www.theguardian.com/business/2017/mar/03/brexit-uk-car-industry-mini-britain-eu
Brexit porn says building new warehouses to store parts and employing stock clerks and security guards will help the economy!