Ancestry adds London Directories 1736-1943

Nearly 20 million records are in Ancestry's new London, England, City Directories, 1736-1943 collection.
The index was created using text recognition software, not transcribed, with indexes of the directories for every fifth year. Expect OCR errors.
The originals, from the London Metropolitan Archives, comprise street, commercial, trade, court, and post office directories.
Check that directories for the borough/area and time period of interest are included to avoid fruitless searches.