One of the things former Spice Girl Victoria Beckham's son, Brooklyn, made headlines for this week was sharing "the world's most expensive" wine with his wife, Nicola Peltz. It was reportedly an 1831 vintage Château d'Yquem valued at around $33,000 a bottle. That got our money correspondent Susan Edmunds thinking about wine, including how you might go about investing in it. She spoke to Lisa Owen.