Explain the allusions "Cock-lane ghost" and "sister of the shield and trident" in A Tale of Two Cities.

In "A Tale of Two Cities," the Cock-Lane ghost is an allusion by Charles Dickens to the haunting in the 1760s of an apartment on Cock Lane, an alleyway adjacent to Smithfield's market near St. Paul's Cathedral.

As the story goes, a William Kent from Norfolk became romantically involved with two daughters from the same family; in 1756 he married Elizabeth Lynes, but she died in childbirth and the baby died a few minutes later.  When Elizabeth's sister, Fanny, moved to London she settled with Kent in an apartment on Cock Lane, but they could not marry according to the Canon law of the Anglican church.  This apartment was owned by a Mr. Parsons.  When Kent went to the country, he asked Parsons's daughter, Elizabeth, to keep Fanny company.  On the first night together with Fanny, the two women complained of hearing scratching noises, and Fanny interpreted them as an omen of her approaching death.  Later, other witnesses attributed this scatching to Fanny's sister Elizabeth who was upset over Fanny's living with her husband in an illicit relationship.

After William and Fanny moved away, the scratchings continued; Parsons torn out the wainscotting in an attempt to discover the cause, but nothing was found.  However, after the death of Fanny, the mysterious scratchings continued and the legend began that "Scratching Fanny" had not died of smallpox, but had been murdered by William Kent.  The story became infamous while William Kent remained under suspicion.  Even Parsons and his daughter were under judicial after an experiment was conducted with Elizabeth in the bed at the apartment.  Witnesses claimed that Elizabeth had made the scratchings herself.  After two nights of listening, the authorities told Elizabeth that if no more noises were heard, she and her father would be put in Newgate Prison.  When Parsons was put in the pillory, he nearly lost his mind, and was released.  Meanwhile the Protestant churches and Anglican Church engaged in controversy over the question of the ghost.

  In Chapter 1 when Dickens writes that "Spiritual revelations were conceded to England at that favored period" of 1775, he alludes to all the interest and sensationalism followed the Cock Lane haunting; yet, the messages of the forthcoming American Revolution were ignored as well as the increasing violence in the country.  Drawing a parallel to France, Dickens describes it as "less favoured on the whole as to matters spiritual than her sister of the shield and trident." (the shield and the three-pronged weapon spear were used in gladitorial combats in Rome, which, of course, lost its empire.) France, too, has its cruelty in its repressive social system in which inflation was rampant and in which a man could be tortured and put to death for not bowing to a procession of monks.  Likewise, France is to be affected by a revolution.