In my naivety, I had thought that the difference between the Holyrood and European Parliament voting systems would mean that I wouldn't have to spend any time over the next few weeks debunking the familiar claims that everything would be right with the world if only SNP supporters would "vote tactically" for the Greens or other radical left parties. I assumed that a simple system in which every elector just casts a single vote for a single party, and in which seats are allocated in proportion to the share of the vote each party receives, would encourage the Greens to just concentrate on making the positive case for a Green MEP to be elected. But nope, it seems they just can't help themselves. Here is what Green parliamentarian Mark Ruskell had to say on Twitter a few hours ago -
"Having a chat with a couple of SNP voters today, had to remind them of the disastrous ‘get Tasmina as our third MEP’ campaign was at the last Euros, just let UKIP in through the backdoor. Polling shows Greens are front runners to take the seat off UKIP and keep Farage out."
That tweet is so spectacularly dishonest on multiple counts that it's difficult to know where to start. First of all, it's true that the Greens made an extremely contrived pitch in 2014 that there would be a better chance of preventing UKIP taking a seat if SNP supporters switched tactically to the Greens. The idea was that the SNP were 'guaranteed' to win two seats, and that thereafter the D'Hondt calculation would divide the SNP vote by three, meaning that excess votes would be wasted on the SNP, leaving the Greens as the only progressive party that could stop UKIP grabbing the final seat. But the snag for Mr Ruskell is that this claim was not, as he implies, borne out by the eventual result. Quite the reverse, in fact. The D'Hondt calculation for the final seat was as follows...
Liberal Democrats 95,319
Now, of course, the Greens would argue that the fact they were in fifth place for the final seat is somewhat misleading, because the numbers for the parties above them were (with the exception of UKIP) affected by D'Hondt, and that what you therefore need to do is look at the absolute number of extra votes each party would have needed to pip UKIP for the last seat. But even if you look at it that way, the SNP would have needed 32,100 extra votes, and the Greens would have needed 32,230. So the SNP were undoubtedly closer on any measure, and if we were being cheeky we could even claim that this proves Green supporters were to blame for letting in David Coburn because they failed to tactically vote SNP. In reality, that would be very silly, because under this voting system it's almost impossible to know which way to vote if you want to cast a tactical, negative vote against a particular party. The only way in which it might be possible would be if you knew in advance, and in precise detail, how everyone else is going to vote - and you can't know that, because opinion polls simply don't offer that extreme level of accuracy. (Some would argue that they don't even offer a basic level of accuracy.)
There's also a rather amusing contradiction between the logic of the Greens' pitch for tactical votes in the European election, and the logic of their pitch for tactical votes in Holyrood elections. As you might recall, I've always conceded the point that the Greens are technically correct that it would be possible to reliably "hack" the Holyrood system and get extra pro-independence MSPs, but only if the tactical voting on the list is extraordinarily widespread. Much more likely is that it would be small in scale, and at that sort of level it would be much more likely to backfire, and could even up reducing the number of pro-indy MSPs. The response I usually hear to that reality-check is: "You're thinking too small, James! With the power of the Yes movement ANYTHING is possible!" And yet implicit in the call for tactical votes in the Euro elections is that you don't actually need to worry about anything more than a very small number of your fellow SNP supporters doing it. If you did need to worry about that, you wouldn't be remotely tempted, because you'd know that if the tactical voting drive was too 'successful' and if every SNP supporter 'lent' their 'excess' vote to the Greens, there wouldn't be two guaranteed seats for the SNP. There would in fact be zero seats for the SNP. In Euro elections, you can't use one vote for your favourite party and then use another vote tactically. We all just have one vote, and if the SNP don't get enough of those, they won't win any seats at all. Simple as that.
To turn to Mr Ruskell's claim that "polling shows Greens are front runners to take the seat off UKIP and keep Farage out", there is no truth in that whatsoever. Thus far there haven't even been any full-scale Scottish polls for the Euro elections. All we have are a few Scottish subsamples from GB polls, and they simply don't offer any comfort to the notion that the Greens will be involved in a direct fight with either UKIP or the Brexit Party for the final seat. For example, of the three YouGov subsamples to date, one has suggested that both the Greens and the anti-Europe parties will miss out on a Scottish seat, one has suggested that both the Greens and the Brexit Party will take a seat, and only one has suggested that the Greens will take a seat and the anti-Europe parties will fall short. Even in the latter example, the Greens were not projected to be the ones responsible for Farage's failure - in fact, the final seat was effectively a scrap between the SNP and the Tories, with the SNP marginally coming out on top. So maybe the clarion call should be "Green supporters must vote tactically for the SNP to stop the Tories!"
A broader point is that there may be circumstances in which it's not arithmetically possible for any party to stop Farage. In a proportional representation system, if the Brexit Party get a big enough share of the vote, they'll be awarded a seat, no matter how the votes are shared out between the other parties. That being the case, it's much wiser to focus on which party you want to win a seat, and not which party you want to fail.
So the answer to the question "which party should independence supporters vote for in the European election?" is SNP if you prefer the SNP, and Green if you prefer the Greens. If you're not that bothered between the two parties, my own personal opinion is that you'd make a bigger statement about independence by voting SNP. Votes for the Greens will probably be interpreted in London media and political circles as environmentalist and left-wing votes, and not primarily as votes for independence.