This is the UK. Just because something is obvious doesn't mean that conservatives and NIMBYs are going to accept it until they, personally, are sitting in the dark.
The North-South interconnects are already happening. The Western HVDC became operational in 2019[1], and two separate Eastern HVDC links (Eastern Green Link 1 & 2) are pretty far along in the planning process, with EGL1 expected to begin construction this year and EGL2 in 2025[2].
This is the UK. Just because something is obvious doesn't mean that conservatives and NIMBYs are going to accept it until they, personally, are sitting in the dark.