::groans:: ;o)

Here - Stukeley gives this information as to the size of a cubit:
"LET us now set about an examination of the measures of the temple itself. Take a staff 10 foot 4 inches and ¾ long. Divide it into six equal parts. These are the cubits of the ancients. Each cubit is divided into six parts. These are palms. Thus have we the original measure of the founders of Stonehenge. We will take Mr. Webb's measures, and compare ’em herewith."

And furthermore:
"Mr. Webb says, p. 55. that the whole work of Stonehenge being of a circular form, is 110 foot in diameter. But to be precise, ’tis 108 and somewhat more, and his own scale in his ground-plot shows the same. This is the diameter from outside to outside, which in our ground-plot is the principal diameter. The thickness of the stones of the outward circle, he says, p. 59. are 3 foot and an half. Hence the inner diameter becomes almost 102 feet English. If the reader pleases to measure 102 feet upon the comparative scales, which I gave of the English foot and Hebrew cubit, being the measure us’d by the Druids, or in the scales at the bottom of the ground-plot, he will find that it amounts exactly to 60 cubits."

Source: http://www.sacred-texts.com/neu/eng/str/str05.htm

So a cubit, according to this, is 1/6 of 10ft 4 3/4 ins. Blimey...

There's loads of references to The Temple of Soloman being 60 cubits, too...

Still trying to find reference to the diameter of the Royal Circus online...

G x