It’s 3pm on a warm early summer’s day. You’re in the park, a picnic basket beside you, watching your date tuck into an ice-cream. Birds are singing, children are chuckling playfully nearby. Things are going well: your date’s handsome, kind and the conversation is good. But something’s wrong. It starts as a tickle in the back of the throat. Then your eyes start itching and soon your nose is streaming. Suddenly, you’re sneezing uncontrollably and, hang on, are you … crying?