The UK production location isn't the only place where BMW builds Minis, as the former Volvo/Mitsubishi/Smart NedCar plant in the Netherlands has been tooled to build some of the 360,000 Minis built yearly. According to the BBC, UK Business Secretary Greg Clark considers the choice to build EV Minis in Britain a "vote of confidence" despite Brexit, and that it would see battery technology development boosted in the UK. By the time the EV version starts production, UK will likely have already left the European Union.
The electrification of the Mini is part of BMW Group's continuing addition of full-electric or plug-in versions to all its brands and model series. Of all the vehicles it will sell in 2025, 15-25 percent will be electrified in one way or the other. Similarly to Volvo, BMW sees flexible production to be in a key position in the future: The facilities would have to be able to build all versions at the same time, as markets fluctuate depending on incentives and infrastructure. If EVs sell strongly, the production process can quickly respond to the demand.
An electric Mini underwent trials back in 2008, so the full-scale production vehicle would have over a decade's worth of engineering behind it.