One Nation is quite a nice sounding political label, but it does not really apply to the Tories and arguably never did.
Support for both Tory and Labour has always been skewed demographically and geographically, concentrating their vote in a way which rewarded them with a disproportionate number of seats.
The Liberals, SDP and then the Liberal Democrats, on the other hand have always drawn support from across the country and from all types of voters who share the vision of a fair, free and progressive society.
The result has been that it has always been much more difficult to win seats under FPTP.
If LibDem support at the next election remains at a high level and there is, as seems quite likely, another hung parliament, we must have electoral reform.