I did read a long time ago that if the power grid goes down, that's the British power grid, no transformers or other parts are kept in stock, its down to the old "just in time" delivery method again, it would take about 3 months to order, make and ship each individual part, if more than just one has failed it would take 2 years to replace the entire system, that's 2 years without power, not only would the economy be down the pan by that time but about 90% of the population would have died of starvation, dehydration, disease and violence.