Former Tory PM warns Labour would use role in government to breakup UK . Labour leader accuses him of being 'silly and over the top ' in speech . Polls suggest Labour will prop up a SNP minority government .
Former Tory PM warns SNP would use role in government to breakup UK . SNP leader accuses him of being 'silly and over the top ' in speech . Polls suggest SNP will prop up a Labour minority government .