Manchester Opera House Show built around Stock Aitken Waterman's songs flies so long as the pop classics are playing Having been born at the end of the 1970s and come of age in the 1980s, or the last time pop music was truly great, there was no sweeter spot from which to appreciate the genius of the Stock Aitken Waterman Hit Factory. To see the triumvirate of Mike, Matt and Pete on stage at the curtain call of this m…