The Conservative strategy of whipping up hysteria about the dangers posed by an imaginary alliance between Labour and the SNP was interpreted by many political commentators as a way of frightening UKIP voters back into the fold.
According to a YouGov poll released just before election day, one in three UKIP voters feared Ed Miliband would share power with the SNP after the election.
It was obviously in Nicola Sturgeon's interest to intimate that a deal between Labour and the SNP would be on the cards if Labour got the most votes. Miliband's categorical denial of this - even to the extent of saying he would rather not gain power if it required the backing of the SNP - is likely to have been perceived as deeply insulting to the Scottish people. It created the impression that Labour, like the Conservatives, saw the SNP as some sort of devious, malign force, rather than as a political movement that represented a large number of Scottish people - some of whom wished to split from the UK all together but others who just wanted more say in decision making.
This suited the SNP agenda brilliantly as it ensured that after this election, many more Scottish people would, in the light of Miliband's perceived distaste for them, see an independent Scotland as the only way forward.
David Cameron is said to be a committed unionist but he took a risk in exacerbating the tensions between Scottish and English voters. Others in his party, it has been suggested, would be quite happy to see Scotland leave the UK - thus greatly enhancing the chances of a right-of-centre party being elected to office in England on a regular basis.