Judging by the way the voting appears to be going for next month, there may be a case for introducing the single transferable vote.
Isn't that what we've got?
If there are only three candidate tunes then it is similar but not quite the same. In our system you can transfer your single vote at any time up to the close of poll. And if, as the deadline approaches, your favourite tune is clearly last in the running then there is some incentive to do so. But since at any moment before the poll closes there is still time for new or transferred votes from others, it is possible that your favourite would turn out not to be last after all. So, even with only three tunes in the field, the vote transfers occurring under our system could be quite different from those that would occur as part of the counting process under STV, thus leading to a different outcome.
And this divergence is hugely amplified where there are more than three candidate tunes to start with. Under STV your vote remains in the count as minority candidates are successively eliminated, it being transferred to remaining candidates according to your second, third etc preferences. In other words, once the count process has whittled the field down to the final two tunes you still in effect have a vote between these two, so long as you have registered a full list of preferences. But this is not necessarily the case under our system, where you can register only one choice. Here, for your vote to count in the equivalent way requires you to be able to figure out, at the moment of your final decision, not only what would be the first tune to be eliminated under STV, but also which other tunes would subsequently be eliminated in turn - this depending on the second, third etc preferences of all other voters, about which you have little or no information, and also on their ability to figure out all of this too. So the chances of this system producing the same result as STV are remote.
In a nutshell: even when there are two tunes clearly out in front of all the others as our deadline approaches, these are not necessarily the two tunes that would survive through to the final elimination in the counting process under STV. And the more tunes there are in the field the less likely this is, roughly speaking.
btw where, as in TOTM, there is only one candidate/tune to be selected, STV is usually called Alternative Vote, or
Instant Runoff.