In today Western Mail Dr John Cox argues that the implication of AV could result in Plaid MPs be wiped out at Westminster especially when taking into account the proposals for larger consultancies in this I am in agreement it is of interest that the Lib-Dems could also lose their three seats and this also seems likely though on the current polls they would do so anyway.
Though I suspect that the Lib-Dems with some misgiving would sacrifice their 3 Welsh seats for the chance of ay 20 -40 more in England and perhaps wiping Plaid and the SNP out
Of course this should not be a reason to oppose AV if it resulted in a truly proportional representation but unless you looked at this from a purely UK angle in which the nationalist parties and all the Northern Ireland parties would probably not meet a percentage threshold then of about 5% giving them a nominal entitlement of 3 MP's then this will not be fair.
Of course in Northern Ireland the London parties do not largely stand so there may be a case that the introduction of AV would result in more proportionality. But the fact that they recognise the uniqueness of the Six counties is an Tacit acceptance by the London parties that "Regional " factors should be included in any assessment of whether a system is proportional or not.
My argument is that although in a minority when it comes to Westminster elections both Plaid and the SNP have enough support to claim seats in the Commons based on the idea of proportional representation. It would be a shame if the introduction of AV could result in them having less representation than they are entitled to under a proportional system based on the Welsh or Scottish percentage of votes,
At the moment Plaid's could claim that it was entitled to 4-5 of the 40 welsh seats based on its votes in Wales, where the SNP cou;ld claim 11-12 instead of the 3 and six they currently have.
I think Plaid's leadership should make a step of rejecting AV not because it threats theircurrent seats but because it is con masquerading as given us more democracy ,as Dr Cox points out this may well be far from the truth in Wales at least.