In an exclusive interview, John Swinney says he feared for his party when he stood to become leader earlier this year.   Speaking to David Clegg, the first minister reflected on the fast-paced first weeks in office, propelled from a think-tank event in London into the top job in Scottish politics.   Mr Swinney explains why he'd turned down a job from Humza Yousaf only a month before he resigned, and details why he thinks he's the right man to reverse his party's decline in the polls as voters become fatigued from 17 years of SNP dominance.