The conclusion
arrived at here is that of Henderson, but it is reached independently.

The history of the letters must be given in summary. Henderson, in _The
Casket Letters_ (1889), was the first to publish and use as evidence a
document of which the existence was made known in the fifth report of
the royal commission on historical manuscripts. It is a sworn statement
of the earl of Morton, written in 1568. A silver casket (originally
Mary's property, but then in the possession of Bothwell) was placed in
his hands on the 20th of June, and was inspected by several nobles and
gentlemen on the 21st of June 1567. Morton denies that the contents, the
letters, sonnets, and some other papers, had been in any way tampered
with. But if Moray could knowingly submit garbled evidence, Morton's
oath is of no value if uncorroborated.

Mary was, on the 21st of June 1567, a prisoner in Loch Leven Castle. A
messenger was at once sent from Edinburgh to London with a letter from
Lethington and a verbal message. By the 12th of July, de Silva, the
Spanish ambassador, reports on the authority of the French ambassador
that du Croc, French envoy to Scotland, avers that Mary's Scottish
enemies have autograph letters of hers proving her guilt, and himself
possesses copies. Of these copies no more is heard, and they cannot be
found. According to de Silva, Elizabeth said that she did not believe in
the Letters, and that Lethington, who wrote to Cecil on the 21st of
June, and sent a verbal message by the bearer, "had behaved badly in the
matter,"--whether that of the letters, or in general. On what evidence
she based that opinion, if she really held it, is unknown. In December
1567 the Scottish parliament was informed that the letters were _signed_
by Mary (they are unsigned), but the phrase is not used in the
subsequent act of parliament. The letters were exhibited and apparently
were read, probably read aloud. Mary's party in September 1568 declared
that they were garbled, and that the handwriting was not hers. In the
end of July 1567 the earl of Moray, Mary's brother, passing through
London from France, told de Silva, as de Silva reported to his
government, that there was proof of Mary's guilt in a letter of three
double sheets of paper _signed_ by her.

According to Moray's version of the letter, Mary was to try to poison
Darnley in a house on the way between Glasgow and Edinburgh where he and
she were to stop. Clearly Lord Livingstone's hou