PAISLEY, SCOTLAND - APRIL 29:  Mhairi Black, the twenty year old SNP candidate is the youngest person standing in the General Election she is going head to head with Labours Douglas Alexander in Paisley and Renfrewshire South on April 29, 2015 in Paisley, Scotland. According to recent polls she there is a strong possibility that she is about to take the seat from Douglas Alexander in what should be one of Labours safest constituencies.  (Photo by Jeff J Mitchell/Getty Images)