The publication yesterday of the donations received by both sides in the referendum campaign over the past six months is the first time that voters in the UK have had access to such information before the ballot.

And with just 70 days to go until decision day, a breakdown of the figures provides interesting clues to the nature and spread of the support for Better Together and Yes Scotland.

To date, nearly £4 million in donations to six registered campaigners have been reported to the Electoral Commission. The donations relate to the period between December 18 and June 26 (the first of four periods for which reports on funding will have to be provided before the poll) and consist of a few very large gifts and a number of smaller ones. The figures show that, in total, Better Together received £2,406,475 while Yes Scotland was given donations of £1,160,000, which means that those fighting for Scotland to stay in the UK received around £1.2m more than the Nationalists.

But what is perhaps more significant than the totals is who provided the money. The vast majority of the cash given to Yes Scotland came from just two sources: Colin and Chris Weir, who won £161m on the EuroMillions lottery in 2011, and Brian Souter, the chairman of the Stagecoach Group and a long-time supporter of the SNP.

The donations for the No campaign, on the other hand, look slightly different. There have also been big donations (the largest being the £1m from JK Rowling, the author of the Harry Potter books) but, while the money from Yes came from just five sources, the £2.4m for No came from 38. This could be interpreted as showing that the No campaign has a broader appeal and is attracting more money from a wider range of sources.

But caution is needed as the figures relate only to donations of more than £7,500 and, with small donations excluded from disclosure for now, it is difficult to draw firm conclusions about which side has the wider reach or greatest appeal to the grassroots.

On this point, the Yes side said yesterday it had received relatively small donations from nearly 11,000 people totalling £194,173 in the past two months. It also tried to dismiss the longer list of No donors as old-school vested interests, except that there are significant business voices in the list and the support of the distillers William Grant & Sons for Better Together, to which the business has donated £135,000, could prove significant.

However, yesterday's figures can only provide a snapshot, a glimpse of landscape through a keyhole, and the final spend will not be known until after the referendum. There have already been claims that taxpayers' money has been misused by both sides on campaign literature; there has also been the suggestion that Yes Scotland being supported so heavily by the Weirs is unhealthy.

But what matters more than any of that is financial fairness. The poll must be paid for, but it must be paid for fairly and openly so that no-one can say, after the result, that money played too great a part.