Ettrick, Tweeddale and Lauderdale

Ettrick, Tweeddale and Lauderdale ought to be safe Liberal Democrat territory, having been represented by David Steel from 1965. Yet it has become Scotland's only four-way marginal. Only six percentage points separate the four contenders.

Jeremy Purvis took the seat in 2003, though his party's vote had dropped nine points. The justice spokesman has had to fight the seat as a marginal and claims credit for returning railways to the Borders.

The Tories lost the seat 42 years ago, and Derek Brownlee was placed fourth in 2003, just 71 votes behind Labour. Mr Brownlee was brought into the parliament in 2005, after David Mundell left Holyrood to become Dumfries MP.

Labour's Catherine Maxwell Stuart has a local aristocratic background that may do her no harm, having stood for the seat before. But the one who should be worrying Mr Purvis most is Christine Grahame, a two-term list MSP for the SNP. She was within 538 votes of unseating the Lib Dems in 2003.