The word moonraker designates a native of the county of Wiltshire, in southern England.
The English antiquary and lexicographer Francis Grose (1731-91) explained the word in A Provincial Glossary, with a collection of local proverbs, and popular superstitions (London, 1787):
Wiltshire moon-rakers. Some Wiltshire rusticks, as the story goes, seeing the figure of the moon in a pond, attempted to rake it out.
Whether this is the story to which Grose was referring is not known, but a detailed anecdote had been published in The European Magazine, and London Review in September 1783. In The wise men of Wiltshire, a contributor signing himself A. B. wrote that, during an excursion to Bath, he noticed a pleasant village “that lay near the extremity of Marlborough Downs, at a little distance from the road leading to the Devizes”. He met an elderly gentleman “perfectly acquainted with that part of the country”, who told him, among others, the following anecdote:
Some years ago, the exact date I was never able to ascertain, one of the most respectable of the inhabitants, returning, on a moon-shine night from the ale-house, thought he perceived, in a pond which lay adjacent to the path, a large cheese. Blessing his starts for so lucky a discovery, and considering it as an earned of fortune’s favours, he hastened home for a rake, to secure so valuable an acquisition, before it should be observed by any other person. In vain, however, he raked, for the versatile cheese, eluding the prongs, he could not bring it to land, notwithstanding he exerted his utmost efforts. An exclamation breathed rather too loud in the anguish of disappointment, reached a neighbouring cottage, and brought forth the rustic tenant of it; who seeing his fellow villager thus employed, without uttering a word, ran in for his rake, and engaged in the visionary pursuit. The alarm being now given, every rake in the parish was employed upon this important business; whilst every woman and child stood anxiously looking on. But an envious cloud at length intercepting bright Cynthia’s beams, her image suddenly disappeared; and the disappointed villagers, supposing the cheese to be sunk by some means or other into the mud at the bottom of the pond, retired to their cottages full of vexation. This proof of more than Athenian penetration, observed the old gentleman, is the chief feather in their caps, and has obtained them the honourable denomination of the Moon-Rakers.
The word moonraker is first attested in Philalethes again! Or, Candidus unmasked! (London, 1767), a religious pamphlet by Thomas Randall. The fact that the word was used as a synonym for idiot, with no explicit reference to Wiltshire, seems to indicate that its usage was already well established:
If one here and there hath used a simple, a foolish argument, will he from thence infer that none of us can produce a good one? Must we all, and the Doctor among the rest of us, claim affinity to the sons of Gotham*, and be despised as meer [sic] ideots [sic] and moon-rakers?
(* Gotham: the name of a village proverbial for the folly of its inhabitants)
In Wiltshire a more complimentary turn is given to the story. The men were in fact raking a pond for kegs of moonshine (i.e. smuggled brandy). Suddenly confronted by the revenue men, they raked the surface to conceal the submerged contraband with ripples, and claimed that they were trying to rake out a large round cheese visible in the pond.