Why does anyone see the need to take a perfectly delightful movie – When Harry Met Sally – and turn it into stage play? “Why take a quintessentially 80s-America, middle-class masterpiece, a diffidently murmured poem to interpersonal navel-gazing, played out in close-up and tight two-shots, and whack it on one of the biggest stages the 21st-century West End has to offer? Why? Why?”