Our Scotland Political Editor Peter MacMahon spoke to the Prime Minister during his visit to the Scottish Conservative Conference.
Watch the full interview on independence - and how it could affect the border - here:
More top news
The Government has announced a 16 million pound investment to electrify the Windermere rail line - but what are the benefits?
A look ahead at the forecast for the Border region.
This autumn is on course to become the third mildest on record.