Everyone says the referendum will be “all about turnout”, and notes the potential impact of differential turnout, but few attempt to give much insight into exactly what that means in practice for both campaigns. There are, however, a few signs of various factors at play on each side of the referendum.

It was interesting to see in Lord Ashcroft’s poll this morning that behind the headline shifts in the total numbers intending to vote Leave or Remain, there are also qualitative shifts in the commitment of each side’s supporters to their cause. Particularly, it seems that the Leave vote is hardening in its certainty both to vote and to vote to get out of the EU – good news for Leavers if turnout overall is relatively low.

The relative softness of the Remain vote means, of course, that it might be a bit easier to persuade some to switch sides. But it also means some of them might not end up voting at all. This raises the question of whether expectations of the result might also impact voting patterns. Most polls and surveys – including ConservativeHome’s – and the betting markets indicate a widespread expectation that Remain will probably win on 23 June. That’s a sword that could cut both ways – it might demoralise Leavers, undermining their campaign effort and encouraging their voters to stay at home, or it might lead Remain voters to stay away, taking the result as a given which does not need them to ensure it.

It’s interesting to consider whether that factor might have been at play in Scotland, but in reverse. The YouGov poll which showed Yes ahead just days before the referendum sparked frenetic activity from the Better Together campaign, and it’s also easy to imagine that some more apathetic unionists might have been spurred to get out and vote when faced with the very real threat of Scottish independence becoming a reality.

With the media assuming a Remain victory, the pro-EU campaign doesn’t have the same panic factor to motivate its vote – and given Ashcroft’s finding that Remain voters are relatively less certain of their cause than Leavers, that absence might depress their vote a bit.

There have been some interesting snippets in the news over the last few days about possible turnout issues among some specific groups of voters, too.

First, students. Several cringeworthy attempts by the pro-EU campaign to harness the youth vote – including “Talk to Gran” and this week’s “Workin, earnin, makin, votin” effort (branded “patronisin” by the Telegraph) – don’t seem to have deterred the student vote from broadly breaking for Remain. However, polling well among students does not guarantee victory – as Ed Miliband could attest. Last week, the FT reported that not only are 63 per cent of students unaware of the date of the referendum – something that campaigning can fix relatively easily – but 56 per cent are registered to vote at their term time address, which is a more intractable problem.

Expats are another group the Remain campaign are keenly targeting, hoping to inspire worries that Brexit would end their residency rights. However, the Electoral Commission’s recommended deadline for applying for postal votes has already passed, and just 196,000 of the estimated 5.5 million Brits abroad have registered – a registration rate of 3.5 per cent. That’s 82,000 up on last year’s General Election, but still leaves expats as a distinctly underpowered group, on whom it might not be wise to base a referendum campaign.

As well as those two target Remain groups, there’s one demographic which Leave is targeting where there might be problems, too: members of the Armed Forces. In recent days, Vote Leave has made a concerted effort on the defence and security front, unveiling several retired generals as supporters this week. However, the Telegraph reports that 27 per cent of the Armed Forces are not registered to vote – due in part to their highly mobile profession. At 73 per cent, their registration rate is still a lot higher than that among expats, but it is about 12 percentage points lower than the population at large.

Of course, each of these groups individually is only a small minority of the electorate. But with differential turnout now the name of the game, each could matter in its own way.

There are signs already of some intensive targeting efforts in the campaign. Postal votes go out over the next few days, meaning that referendum day for millions of voters is already upon us. Both campaigns have been delivering leaflets to target postal voters, with two million expected to be delivered in the next couple of days by Vote Leave alone.

Which will succeed? As Lord Ashcroft always notes, the polling is a snapshot, not a prediction – and with so many factors at play, the effectiveness of the targeting operations could make all the difference.