Without Trident the Government of the day can wave good bye to all the votes in Scotland and most of them in the NW of England.
I don't think the Tories would be too bothered about losing votes in Scotland. I think they may encourage Mr Salmon to have his referundum and see the back of Labour forever. As for NW England, well now that the Japanese have finally agreed to take back their nuclear waste, and least one of the major production facilities should be in business for a fair while yet. The lads at Barrow could diversify into tractors or superguns.