Katy Perry’s sweetly forgettable fifth album, Smile, comes straight out of the primary school colouring book. Musically as well as lyrically, the whole record blu-tacs itself firmly to bright’n’boring basics.As a fan of Perry the human being – admiring her sane survival of both her oppressive religious upbringing and her marriage to Russell Brand, who dumped her by text – I find myself delighted that she is making such a safe recovery after frightening struggles with her mental health.