1950s
In 1951 after the repeal of the last of the witchcraft laws in England, Gardner went public as a witch and broke off from Old Dorothy's "New Forest Coven" forming his own. According to his account much of his new Coven's Book of Shadows was based on the New Forest Coven's.
[Note: I now have reason to believe that Gardner actually broke off from Old Dorothy's coven prior to 1951 and simply did not go public about his own coven until the laws were repealed.]
In 1953 Gardner met Doreen Valiente and she was initiated into his Coven. Doreen opposed how much of Gardner's Book of Shadows was "borrowed" from Aleister Crowley. Gerald and Doreen rewrote Gardner's "Book of Shadows" and developed the original form of Wicca now known as "Gardnerian Tradition".
In 1954 Gardner wrote a book called "Witchcraft Today" which became quite popular and Gardnerian Covens were being started all over England.
1960s & '70s
'80s & 90s
In the early 1960s Wicca started appearing in the United States. Wicca caught on quite quickly because the rebellious, earth centric basis of Wicca fit right in with the 60s eco-friendly hippy movement.
In the 1960s and 70s many new traditions were created. While a few will argue this, they were all based somewhat on Gardner's work. Alexandrian Wicca is one of the oldest and very near to original Gardnerian. Seax Tradition, Faery Tradition, and Dianic Tradition are well known, and there are countless others.
By this time many aspects of the original Wicca had fallen from popularity in the new traditions; Things like ritual nudity, and sexual activity as a central part of ritual were replaced with more conservative practices.
[NOTE: Yes, both ritual nudity and sexual activity during ritual were both a significant part of the original Wicca.]
Mid 1970s
By the mid 1970s Wiccan practice came to the attention of the academic community and the history of Wicca was examined.
Gardner claimed that Wicca was "The Old Religion" and that the ritual and Book of Shadows were both based on the practice of the New Forest Coven which had an unbroken lineage back to the practice of Witchcraft in the dark ages. Gardner's claims about New Forest were generally accepted at the time. People flocked to what they believed to be the religion of their ancestors and for the most part accepted Gardner and the others on their word.
People practicing Wicca were told it was thousands of years old, only to find out from the academic community that significant parts of it were written in the last 25 years. As you can imagine this caused quite an uproar. First there was a lot of academic bashing, then people felt betrayed and lied to by the Wiccan community.
We now know within reasonable doubt that some major aspects of Wicca are recent, borrowed from Freemasonry, Ceremonial Magick and the books of Margaret Murray, Charles Leland, and Aleister Crowley among others.
[NOTE: Sad as it may seem, people new to Wicca are seldom told the truth about the history and still to this day believe they are practicing an ancient religion.]
[NOTE: The history of Wicca may be rough around the edges, but this doesn't change the legitimacy of it in my opinion. Wicca is a wonderful religion that is empowering and enlightening.]
Keep in mind, up to this point (for the most part) the only way to learn Wicca was to join a coven practicing it.
1980s and the New Age
That brings us to the 1980s, and the "New Age" movement. With the dawn of New Age spirituality came an opportunity to make a huge pile of money selling books on Wicca. No longer did one need to find a coven and learn from a teacher, now all one needed to do was visit a bookstore, spend on a couple of books and voila, you're a Wiccan. It became the age of "self-initiation" which was a dirty word to those in formal coven practice.
1990s
Because Wicca was being treated as a "New Age" religion, other practices which had nothing to do with the original Wicca became common in the practice of Wicca. Soon there were pentacle wearing Wiccans with Native American spirit guides, studying Yoga chakras, and practicing Reiki (a Chinese healing technique).
Wicca Today
As you can see Wicca has changed significantly in 50 years, from a secretive dark mystical coven practiced tradition to a New Age solitary practice with self-initiation.
As to Wicca being a direct descendant of ancestral religions, let me say this: In referring to Gardnerian Wicca (circa 1953) there are some aspects of it which are ancient. Almost all of it is not more than 500 years old. A lot of it is less than 150 years old, and a significant amount is post World War II.
.....AND SOME WISDOM FROM THE GREYBOOK
--Because we know that indeed there is a GOD of many Modes, we must acknowledge this Power in the community as well so we may call our future home Gods' Kingdom; The Place we will call home.
Prymus 1-1969
--When you, of The Family find yourself as being a guest of anothers' home, remember who you are and why you are and respect host as you put the host before yourself. In short, mind your manners.
Prymus 1-1969
--He will come as a Great, Great descendent of slaves; from the middle of the Great Country; Born in the city of wind; An artist of various sorts; Inspired by the Ascended Masters, He will found the Family and build our community.
Prymus 2-1983
--Artists do have a diffrent 'air' about themselves than most others; Inwardly and outwardly like the flamboyant Peacock or the enigmas Arachnid.
Prymus 3-1998
--Magnetize!!
Prymus 4/2003.
Family! If you say that you love your mate, then truly LOVE. To take a living being for granted is like one having bad hygeine; Not taking care of the body and allowing lower life forms to digest on your own toxic flesh.
PRYMUS 4
Women should be worshipped and served by MAN resposibly; Although WO/Man are both Divine in Creation, WE ALL COME FROM THE FEMININE.
PRYMUS 1