A curious anecdote was published in Joe Miller's A New Edition of the Old Joe Miller, or, Universal Jester (1810) regarding a change made to the military dress uniforms of the Volunteer Corps in approximately 1802-4 (my estimation). Pitt died in January 1806. Although this dubious incident was reported several years after Pitt's death, William Pitt was Colonel and Lord Warden of the Cinque Port Volunteers at the time of this alleged occurrence:
"Previous to the inspection of the Dover Volunteer Corps by the Lord Warden, on Monday evening, an order was issued for the men to wear black stocks made of leather, as is usual with troops of the line. Several of the corps objected to this order, alleging, that not being accustomed to such a stiff bandage round their necks, they hoped to be permitted to wear their silk ones as before. Mr. Pitt observed, when the corps assembled, he had never been accustomed to wear a stock made of leather, but he now submitted to that part of the military dress, from which he did not experience the least inconvenience. "That may be, Sir, (replied an honest blacksmith, who was in the ranks) for your neck is, like your head, so very long, that the leather can do you no injury" (Miller, p. 59). Needless to say, I'm highly critical of the authenticity of this account, and it's a rather impertinent remark on the part of the "honest blacksmith." I'm no expert on military attire during the Napoleonic Wars, either. I'm relating this here as it's an obscure Pitt anecdote which I have never seen elsewhere.
Miller, J. (1810) A New Edition of the Old Joe Miller, or, Universal Jester. London: T. Hughes, p. 59.