Professor David Daube suggested in The Oxford Magazine of 16 February 1956 that Humpty Dumpty was a "tortoise" siege engine, an armored frame, used unsuccessfully to approach the walls of the Parliamentary-held city of Gloucester in 1643 during the Siege of Gloucester in the English Civil War. This was on the basis of a contemporary account of the attack, but without evidence that the rhyme was connected. The theory was part of an anonymous series of articles on the origin of nursery rhymes and was widely acclaimed in academia, but it was derided by others as "ingenuity for ingenuity's sake" and declared to be a spoof. The link was nevertheless popularized by a children's opera All the King's Men by Richard Rodney Bennett, first performed in 1969. From 1996, the website of the Colchester tourist board attributed the origin of the rhyme to a cannon recorded as used from the church of St Mary-at-the-Wall by the Royalist defenders in the siege of 1648. In 1648, Colchester was a walled town with a castle and several churches and was protected by the city wall. The story given was that a large cannon, which the website claimed was colloquially called Humpty Dumpty, was strategically placed on the wall. A shot from a Parliamentary cannon succeeded in damaging the wall beneath Humpty Dumpty, which caused the cannon to tumble to the ground. The Royalists (or Cavaliers, "all the King's men") attempted to raise Humpty Dumpty on to another part of the wall, but the cannon was so heavy that "All the King's horses and all the King's men couldn't put Humpty together again". Author Albert Jack claimed in his 2008 book Pop Goes the Weasel: The Secret Meanings of Nursery Rhymes that there were two other verses supporting this claim. Elsewhere, he claimed to have found them in an "old dusty library, [in] an even older book", but did not state what the book was or where it was found. It has been pointed out that the two additional verses are not in the style of the seventeenth century or of the existing rhyme, and that they do not fit with the earliest printed versions of the rhyme, which do not mention horses and men. In popular culture Humpty Dumpty has become a highly popular nursery rhyme character. American actor George L. Fox (1825–77) helped to popularise the character in nineteenth-century stage productions