I will start with a few useful links. For a short history of the rise of Wicca and the role of Gardner, see the excellent paper (here) given by Julia Phillips at the Wiccan Conference in Canberra, 1991. For more information on Gardner, see the excellent, and recently revamped, GeraldGardner.com. It is worth looking, in particular, at the Gerald Gardner Archive (here) for press clippings, many from the collection of Melissa Seims of www.thewica.co.uk. I hope to add to these clippings in time. For the complete text of Witchcraft Today (1954) as a pdf click here.
Finally, here is a great, and an uncommon, photo of Gardner. It was published in Arthur Moore's Manx Scene in 1973.
[See here for a larger image]