During his stay in Berlin in 1764, Boswell lived in the house of Karl David Kircheisen, the president of the Berlin city council.
Jean Louis L'Estocq
Referred to by Boswell only as "L'estocq", Boswell on the Grand Tour I, 1763-1764 identifies him as Jean Louis L'Estocq.
According to Boswell, he was formerly (i.e. before September 1764) tutor to the princes of Anhalt-Dessau, probably Albrecht, and Johann George and possibly even to the then reigning Prince Leopold III.
Life with Boswell:
Boswell had some conversation with L'Estocq at the Court of Dessau on September 26, 1764.