The evidence is in the polls and, as you say, recent opinion polls have lost all credibility in providing voters this great assured guidance of trends that have supposedly developed and then, surprise surprise, they've been proved wrong! I think you are better studying the bookies' odds on who will win each electoral seat and you'll have a good indicator of what is really going on. In Scotland the SNP is 'odds on' in over 45 seats with some of the others on 'short odds' as well! I hope the SNP win all 59 seats and send a huge 'two fingered' message to the unionists up here who infect Scottish politics as well as Westminster and it's government!!! I know it is highly unlikely but one can only wish that such huge solidarity and unity would envelop Scotland in the face of some of the most shameless political activities I've ever observed from 2014 onwards!!