Interesting analysis of the Scottish referendum situation by Chris Huhne in The Guardian, with reference to the nail-biting outcome of the Quebec referendum in 1995, which according to Wikipedia had a staggering turnout of 93.52%.
One of Chris Huhne's main conclusions at this stage is this:
The main motive, if Scots opt for independence, will be their desire to shake off the incubus of English conservatism.