Photo by Peter Nicholls / AFP via Getty Images It was 12 years ago when a Labour politician first warned me that the party should be as alive to the electoral threat posed by the Green Party as it was to that posed by the Faragist right. I remember how the candidate in question, new to politics, sat on the edge of his seat and glanced nervously at my Dictaphone. He spoke a little awkwardly and formally, but earnestly, about how, yes, Labour was facing the rise of Nigel Farage’s Ukip – which won the UK’s European parliament elections that year – but that the Greens were also ones to watch out for.  “Given the political instability at the moment, due on one hand to Ukip and to other parties like the Greens, there is a real election to be won and to be fought,” he warned. “The political compass is a little harder to read.” His failure to read that compass, it turns out, has landed Labour in its latest political mess.…