The ill-fated mountaineer George Mallory's only book was "Boswell the Biographer"?
Johan Mikael Blanc
Only identified as "Blanchot" by Boswell. The notes to Boswell on the Grand Tour I, 1763-1764 suggest he might have been a Johan Mikael Blanc. According to Boswell "in the service of the Swedish ambassador" and "a fellow of knowledge and clear expression".
Life with Boswell:
Boswell spend some time with Blanchot and Hübner in Berlin on September 3 and 4, 1764. On the 4th "Blanchot and Hübner drank a glass of wine with me at my lodgings, and Blanchot showed me on the map my route to Geneva, so as to take several German cities and courts in my way."