“No. 101‪”‬

One evening in the January of 1745, the critical year of Fontenoy and of the great Jacobite rising, a middle-aged gentleman, the private secretary of a Secretary of State, was working as usual in the room of a house in Cleveland Row. The table at which he sat was littered with papers, but at this precise moment he had leaned back in his chair with a puzzled expression and his left hand in perplexity pushed his wig awry.
“Extraordinary,” he muttered, “most extraordinary.” The remark was apparently caused by an official letter in his other hand—a letter marked “Most Private,” which came from The Hague, and the passage which he had just read ran:
“I have the honour to submit to you the following important communication in cipher, received, through our agent at Paris, from ‘No. 101,’” etc. On the table lay the cipher communication together with a decoded version which the secretary now studied for the third time. In explicit language the despatch supplied detailed information as to certain recent highly confidential negotiations between the Jacobite party in Paris and the French King, Louis XV., a revel