The bounds of credibility

I am currently researching the writings of a 19th century cleric and JP, whose astronomical theories regarding Silbury Hill and the stone circles at Stonehenge and Avebury are so absurd, so completely beyond the realms even of science fiction, that in spite of his Oxford MA, I really do wonder whether he was educationally subnormal.
 
The Reverend Edward Duke was justifying his theory that the ancient Britons had built Silbury Hill – a large conical mound to the west of Marlborough – to represent planet earth, with the twin stone circles (now disappeared) at Avebury representing the sun and moon, and Stonehenge representing the planet Saturn …
 
Duke had read in a book, Recreations in Astronomy, that the earth is an oblate spheroid – a flattened sphere – and was concerned that people would argue against his designation for Silbury Hill, because a cone was quite unlike an oblate spheroid. He apparently ignored the devastatingly obvious fact that you cannot build an oblate spheroid of the size of Silbury Hill out of chalk and turf …
 
He said, in justification of his theory, ‘those early astronomers … may not have been quite cognizant of the shape of the earth …’ Quite so.
 
I was reminded of Mr Duke and his theory when reading the Daily Telegraph today – I do only buy it for the puzzles, but I could not avoid an editorial commendation on the front page: 
 
Mr Johnson believes in B*****, but also in the greatness of this nation and what it is capable of. We urge readers with a vote to support him
 
I am a patriot, and I too believe in this nation. One of its great attributes is that it supports and nourishes people like Edward Duke and Boris Johnson. I am not at all sure though, that it could survive either of them becoming prime minister …