Manufacturing battery cells is very energy intensive, so I’m guessing that the recent sky-high UK energy prices spooked their investors and made UK battery manufacturing look unviable.
Something like NorthVolt, on the other hand, works because they have access to reliable low-cost hydro in Northern Sweden.
Yes, Northvolt tried building their factory further south in Sweden (Västerås) but was denied due to limited grid capacity. Turns out they were somewhat lucky, since electricity prices are cheaper furter north, and the energy crisis happened!
Something like NorthVolt, on the other hand, works because they have access to reliable low-cost hydro in Northern Sweden.