Liam Kennedy: The global Left – which includes the SDLP – feels tide is turning in their favour

​Blue skies over Barcelona, red banners in the Conference Hall, and a Catalan rock band swaying to ‘Imagine’, John Lennon’s peace anthem. Last weekend saw a gathering of 5,000 activists in the Mediterranean home of Gaudi, Granados, Miró, and Barca football club. They were here to debate socialist and social democratic politics from round the world. The vast hall was overflowing – many could not gain admittance.