Pro-union Leader for the Scottish Liberal Democrats Willie Rennie addresses supporters and journalists in Edinburgh, Scotland, on September 9, 2014, ahead of the referendum on Scottish independence. Rennie was accompanied by Scottish Conservative Leader Ruth Davidson and Scottish Labour Leader Johann Lamont. Britain's three main political parties united on Tuesday to promise greater powers for Scotland if it rejects independence in next week's referendum, in a last-ditch attempt to head off growing separatist support. AFP PHOTO/LESLEY MARTIN        (Photo credit should read LESLEY MARTIN/AFP/Getty Images)