I don't think you can really count the referendum. It was presented as a loaded question and didn't give an option for PR. There was very little in the way of educating the electorate about how AV even worked.
Its a different story now. How can Cameron have a mandate in Scotland where the SNP have swept the board? If you look at votes to seats its clear something is wrong, we have a system when millions of peoples vote to all intents and purposes don't count.
The vote breakdown is current Con 36.8%, Lab 30.6%, UKIP 12.6%, Lib Dem 7.7%, SNP 4.8% and Green 3.7%. Translate that to seats and you get Con 322, Lab 228, UKIP 1, Lib Dem 8, SNP 56 and Green 1. I don't see how anyone can look at that and say the Commons is going to be representative of the votes cast.
We could see three leaders resign in one day.