"If the UK wants PR (surely it does?) then Lib Dem is the only way. Lab & Con are never going to go along with that because they know they have so much to lose!"

Labour had a huge majority at Westminster and yet they introduced PR as the voting system in the devolved Scottish Parliament despite the fact that it was obviously against their interests to do so. Without PR the Labour Party would probably have had a permanent majority at Holyrood whereas they've had coalitions with the Lib Dems and now are the opposition party to the SNP govt. They also introduced PR in Wales where they are now in coalition with Plaid. Surely it will most likely be Labour, albeit with the Lib Dems nagging in their ears, who will eventually introduce it at Westminster too?