@cstross Does it have to be an either/or? My (limited) understanding of how large-scale nuclear reactors work tells me that they need a steady supply of water for cooling. The current projections for the next 50 years suggest that this is going to be increasingly hard in much of England and Scotland is a far safer bet. Improving the grid so that England and Wales can use the electricity is a separate requirement (and, with the lead time on nuclear reactor construction, probably one that can be started later and finished earlier).