Low latency is desirable for stock traders. Most of the data center growth isn't driven by that but by non latency critical workloads such as AI.

The reason, data centers choose to be near London is because there is no pricing advantage to go up north. Even though energy is plentiful, readily accessible, and often curtailed when there's too much of it there. If there was a pricing difference, you'd see a lot more economic activity up north.

Basically the physical advantage is there but the lack of economics cover it up and wipe out the advantage.