It’s genuinely astounding how far off course things have gone. Cliff’s work has undeniably matured since his early days in the 1960s, yet the simple appeal and upbeat music of those earlier projects are now overshadowed by a plot that's frankly absurd, some over-the-top acting from Hugh Griffiths, possibly the worst musical number I've ever encountered – "Brumburger," given the Birmingham setting – and dialogue so un…