Jermyn Street Theatre is a tiny space. And when we say tiny, we mean tiny. We'd guess at 80-100 seats. And if you're over 5ft 10, you can forget about leg room for the evening. Luckily, Opera on the Run's delightfully light-hearted show, The Perfect Picnic should be more than enough to divert your ears and eyes away from any cramp forming in your legs. Recently-redundant David doesn't want to go the opera; he's......