Thomas Earnshaw, 1749-1829, is most famous for his contribution to marine horology, in particular his version of the spring detent which was widely used in preference to that invented by John Arnold.
Having contributed so much in the sphere of precision horology in it quite astonishing that he made only three or four regulators. One such documented clock is that which he was asked to make for the Armagh Observatory in 1794 which was remarkably only the second regulator he had made. In Derek Howse Clocks in the Greenwich list of Observatories, there are three regulators listed, the first for the Armagh Observatory, the second ordered by the Board of Longitude and thence to the Royal Observatory, Greenwich, (now in private hands) and the third for the University Observatory, Coimbra in about 1824.
The latter clock is still listed as missing which brings one full circle to the present clock being offered which was apparently in the offices of the Silversmiths Co. (Goldsmiths and Silversmiths Co.?) until the second world war when it was sold to an American collector.
That it was specifically designed for use in an observatory is beyond doubt, the only question remaining is which one?