Of course this must be the most pressing matter arising from GE15.
In the past I've stood against PR in any form and in favour of FPTP, but the iniquity of the UKIP result has changed the facts. And I always reserve the right to change my mind when this happens. However, there will be little appetite on the Treasury bench to look at this; FPTP works (sort of) with a 2.5 party system, but not with the multi-party result split along national borders that we've just had.
Add to this the urgent problem of boundary changes, where currently the vote of someone in Manchester or East London is only worth a third of the vote of someone in a rural Welsh or Scottish constituency. Equalising constituency sizes to a lesser-developed nation standard of at least +/-5% is essential; achieving the +/-3% level that advanced democracies such as New Zealand achieve must be an aspiration.
My great fear with PR is that we will be deprived of the Balls and Portillo moments. UK elections are usefully brutal at times in reminding politicians who their bosses are. Party grandees tend to be protected under PR, with hopeful newcomers taking the kicks. It really would be a shame to lose the spectacle of a humiliated loser pay for his/her hubris by standing on the returning officer's stage as they are openly shamed.