IS THERE anyone still alive who can remember the heyday of the cowslip? Once as common as ­garden daisies, these ­yellow flowers used to chatter their way across the countryside in such profusion that many Anglican churches celebrated “cowslip Sunday”.A number of hymns were even written to celebrate this sociable spring bloom. In late April and May, East Enders would descend on the fields of Essex and carry great armloads home to freshen and brighten their city lives. Going back further in time, every cottage would have its bottles of cowslip wine and cowslip tea. These days, well, when did you last see a single wild cowslip, let alone a pride of them painting a field gold? People talk of the loss of the great buffalo herds and the shrinking rainforests, but doesn&rsqu