Romans in togas, shepherds in saunas and the Bridgerton garden in bloom ... my wild day at Chelsea flower show

A gigantic Chinese dragon made of gnarled chunks of driftwood towers over a display of bog plants, puffing steam from its nostrils and clutching a ceramic pearl that gushes with water. Nearby, men dressed in togas patrol the courtyard of a pretend Roman villa, where simulated rain pours into the garden from a pantiled roof. Around the corner, a waterfall cascades down an artificial rock face, creating an arresting backdrop to a display of luxury outdoor sofa cushions. Welcome to the RHS Chelsea flower show, a surreal phenomenon that has gone from an annual fair of prized blooms to a…