THERE’S NO HISTORICAL record of deep water diving activity around Denmark Street in London’s Soho. In the 20th Century it became known as Britain’s ‘Tin Pan Alley’, and a blue plaque commemorates the fact, but more observant passers-by will notice high on the face of no.5 another plaque, to ‘Augustus Siebe, 1788-1872, Pioneer of the Diving Helmet.’
Before Siebe, history is littered with attempts to make a practical diving suit. Almost inevitably, Leonardo da Vinci – who seems to have anticipated
