This triangular shoulder bag, from the designer’s new Popular handbags collection, will make a striking addition to any outfit, and will sit especially well with sharp edged retro chic.I’m not entirely convinced that shapes can be in fashion, but right now the triangle is definitely having its moment in the sun. Pyramids and other triangular structures are shooting up all over the place, and Gareth Pugh is one designer who certainly knows how to work an irregular shape…