Could the 40% threshold tactic badly backfire for the #No2AV camp? (#Yes2AV)

Morus has a fascinating post on Political Betting today where he highlights a rather obscure feature of the AV referendum legislation which is that Nick Clegg, who is responsible for the bill and its implementation is actually more empowered by the 40% threshold clause. It means that he can make a judgement call about whether the turnout justifies the change. The 40% threshold is not binding.

Of course if the turnout is very low and the victory is small, with the threshold amendment in place it may be politically very difficult to put the change through. However I can well imagine were the amendment to stand that because the No camp would then have a real incentive to dampen down turnout that we could well find a large majority for change albeit on a turnout below 40%. Let's hypothesise that the turnout is 32% (a good few points below the 40% threshold) but that the figures are 65% for and 35% against. Were the threshold to stand, an outcome like that would be very possible because of how the voting dynamics could be affected. However if you then look at what the actual percentages of those voting yes would be compared to the voting register it would actually be 65%*0.32=20.8%. In other words more than enough to have won the referendum even if the final 8% of abstentions that would have taken us up to the 40% threshold had all voted no. Under circumstances like that I would expect implementing the change would be widely seen as democratically and morally correct.

Of course this is all speculation and the most likely scenario is that the amendment will be overturned and no threshold will apply. That is basically what David Cameron said would happen at yesterday's PMQs.

But there is another twist here. Because the 40% threshold has had so much publicity over the last few days even if/when it is overturned there will be some people who will not be aware of that fact and will still think it applies. Therefore some who were planning to actively vote "no" may well be tempted to sit on their hands assuming an abstention is tantamount to voting "no" or at the very least is a help to the cause. They will be wrong about this and will in fact be helping the "yes" camp. At the same time, of those who were planning to vote yes, if any mistakenly think the threshold applies the incentive will work in the opposite direction and they will be more inclined to vote! And with things so tight, that could make all the difference.

It could be that the 40% amendment tactic by the Lords, even if it doesn't actually make it onto the statute books is the thing that helps this referendum to pass.

Wouldn't that be an irony?