Complex sentence: In due course he became a great friend of the Duke, which led to the latter appointing Blow in 1916 to manage the illimitable Westminster estates which covered vast tracts of Belgravia and Mayfair in London, a position to which the quixotic Blow was completely unsuitable.
Split into simpler sentences: In due course he became a great friend of the Duke, which led to the latter appointing Blow in 1916 to manage the illimitable Westminster estates. These covered vast tracts of Belgravia and Mayfair in London, a position to which the quixotic Blow was completely unsuitable.