There is a famous passage in Julius Caesar's Gallic Wars, where he discusses the Druids; and describes their relationship to Britain:
Throughout all Gaul there are two orders of those men who are of any rank and dignity... But of these two orders, one is that of the Druids, the other that of the knights. The former are engaged in things sacred, conduct the public and the private sacrifices, and interpret all matters of religion. To these a large number of the young men resort for the purpose of instruction, and the Druids are in great honor among them.
For they determine respecting almost all controversies, public and private; and if any crime has been perpetrated, if murder has been committed, if there be any dispute about an inheritance, if any about boundaries, these same persons decide it; they decree rewards and punishments; if any one, either in a private or public capacity, has not submitted to their decision, they interdict him from the sacrifices.
This among them is the most heavy punishment. Those who have been thus interdicted are esteemed in the number of the impious and the criminal: all shun them, and avoid their society and conversation, lest they receive some evil from their contact; nor is justice administered to them when seeking it, nor is any dignity bestowed on them.
Over all these Druids one presides, who possesses supreme authority among them. Upon his death, if any individual among the rest is pre-eminent in dignity, he succeeds; but, if there are many equal, the election is made by the suffrages of the Druids; sometimes they even contend for the presidency with arms.
These assemble at a fixed period of the year in a consecrated place in the territories of the Carnutes, which is reckoned the central region of the whole of Gaul. Hither all, who have disputes, assemble from every part, and submit to their decrees and determinations.
This institution is supposed to have been devised in Britain, and to have been brought over from it into Gaul; and now those who desire to gain a more accurate knowledge of that system generally proceed thither for the purpose of studying it.
From this reference, and other evidence; Britain was the centre of the Druids and their religion of eternal (probably reincarnating) life. It was the main place where Druids were trained by a complex and prolonged process of education and initiations - all done by word of mouth and memorization, because writing this secret knowledge was forbidden.
And the Druids were a problem for the Romans, because they organized and inspired the fiercest resistance they encountered in their invasions and eventual conquests of Gaul and Britain. Caesar comments that the druidic beliefs inspired the Britons with exceptional personal courage in battle, since they did not fear death.
In Claudius the God, Graves makes the destruction of druidry the major objective of the inclusion of of Britain in the Empire - despite that Augustus had originally made it a principle that the boundary would be Gaul. So long as Britain existed to train and export Druids, then Gaul could never be securely subjugated.
After the conquest, it was a major priority to extirpate the Druids and break their power; which is exactly what the legions were doing, a couple of decades later, in North Wales and Anglesey (as described by Tacitus) - when Boudicca mounted her massively destructive rebellion in the opposite corner of the country.
Whether or not these Celtic Druids were in any way descended from the Neolithic/ Bronze Age priesthood who created the vast sacred landscape of southern England around the megalithic monument of Avebury, it is not known.
But it seems clear that there were several times in history - up to the 'Oxford Movement' of the 19th century - when the British Isles has been a major focus for religion, with international significance.
However, Britain was also the place where the industrial revolution began - and the way of thinking we could call 'positivism' or materialism began to be established, and where this eventually achieved perhaps its most thorough triumph; with, here-and-now, the all-but eradication of religion as a powerful motivator in human lives.
Positivism has a fascinating role in the history of human consciousness, if we regard positivism as a development in human thinking - rather than as a response to changed conditions. In other words, if we regard the industrial revolution as a product of positivistic thinking (i.e. Not the cause of positivism).
We need to recognize that positivism was - at first - experienced as a great liberation of the previously-passive human individual from the oppressive constraints of... well of all forms of communal immersion and control (good and bad).
Positivism meant that its adherents felt able to think for themselves for the first time in history - and to experience life from a centre in the individual; and from this centre to evaluate and choose-between the ideas and instructions of the rest of society.
Positivism activated Men's thinking, and grounded it in his self.
Of course we are now at the incoherent, alienated, and self-destroying end-stage of this process - and Britain has become (under the recent domination of its diaspora-nation the USA) an originating and generative centre of materialistic global totalitarianism and (therefore) evil.
But this has been our choice, and the choice of our ancestors.
Exactly because of our individualistic consciousness, we could have chosen otherwise - and still can do - if we wished.
Positivism is not necessarily evil when it is known to be what it was intended (by God) to be: a transitional phase of human consciousness.
If the people of Britain had instead chosen to root their knowledge, lives, culture in God and the spirit - then we could have taken a very different and better path - and so could the rest of the world, if they too had chosen.
It is not a matter of eradicating the mind state of 'positivism' and trying (but failing) to go back to an earlier phase of consciousness; instead we ought to use our innate capacity (and doom) of individual knowing, evaluating, and choosing to create (because this freedom is precisely a form of creation) a world rooted in the spiritual, in God, in context of a perspective of resurrected eternal life - made possible by Jesus.
Consider; in the world here-and-now people believe/ know/ live-by all kinds of weird, nonsensical and evil stuff - and our communal, institutional world therefore operates on the basis of these beliefs; and (by our choice) forces them back upon us.
If, instead, we choose to believe/ know/ live-by that which is true, beautiful and good; then... our world and the communal world would begin to operate on those beliefs.
...It really is as simple, and as difficult, as doing that.
Note added: Another way of thinking about this matter is that Positivism - as such - was actually an expression of divine destiny, and an intended aspect of that line-of-development initiated by Jesus Christ. Its many evils are a consequence of being cut-off from Christianity on the one hand; and also because the Christian Churches cut themselves off from the implications of this new mode of thinking - initially by the Churches excluding and resisting individualism and a spirituality rooted in originative intuition, later (and now) by these same Churches accepting and assimilating-to atheistic-positivism.