Just what does the Scottish National Party want? And what could it mean for the UK?

Douglas Fraser investigates the SNP's long search for an independence vision that works. He talks to insiders about the party's turbulent past, torn, as one leader put it, between 'Jacobites and Jacobins'. How has the party tried to build a vision of Scottish identity that keeps pace with social change? Does it aim to preserve the old British welfare state, or try something different? What do its plans for continued close links with the rest of the UK mean for its vision of a separate Scotland?

Scotland may be diverging more and more from England, whatever happens in next year's independence referendum. With that vote fast approaching, where this debate is heading matters for everyone in the UK. The SNP's journey reveals much about this important change.

Presenter: Douglas Fraser