Answering my own question, are snowdrops wild and Geoffrey Grigson (The Englishman's Flora) has the same problem of identity. And as a note Grigson's book will be the one I pick to take to my 'Desert Island' for the sheer delight of invoking our native plants so tied up with our history and religion.
Firstly, the names this little flower accrued in late medieval times - candlemass-bells, dewdrop, dingle bell, drooping lily, Eve's bells, February Fair Maids to name but a few. He says it may or may not be native, it grew in Elizabethan gardens and was seen as a 'bulbous violet' until the end of the seventeenth century. We probably take its name snowdrop from the German Schneetrophen. The flower was called 'candlemas' for it appeared in February near the date Feb 2nd The Feast of Purification which is of course also the pagan Imbolc time as well. The two religious dates marrying the same celebration. In some counties they were thought of as Death's Flowers and it was unlucky to bring them indoors. The 'wild' snowdrop was first recorded in the seventy-eighties in Glos and Worcs.
I have lately been reading Phil Rickman's books on the clash of Christianity and Paganism, thoroughly fiction, nevertheless he explores both the church and paganism, and his vicar Merrily Watkins, rather an anti-heroine in the stories fights or tries to come to terms with the many and varied aspects of paganism. It reminds me that as a child I read an awful lot of Dennis Wheatley, and devoured every book on ghosts in the library.
What does Grigson say about Dog's Mercury, (Mercury perennis) the answer lies in the use of the word 'dog' it being an inferior plant and poisonous as well.
Its name are thus; adder's meat, boggart flower, dog flower, dog's medicine, snakes flower, etc. It is an emetic and useful for making enemas. In Germany the name Mercury, is translated as Bad Henry, the evil goblin or the evil boggart.....