Letters On England by Voltaire, translated and introduced by Leonard Tancock in the Penguin Classics Edition, is free courtesy of publisher Penguin. This is pretty much bound to be a new-ish, non public-domain version.
Currently free at
Amazon UK. May or may not drop in the other Amazons (I'm guessing not, but I could be wrong).
Description
Also known as the Lettres anglaises ou philosophiques
, Voltaire's response to his exile in England offered the French public of 1734 a panoramic view of British culture. Perceiving them as a veiled attack against the ancien regime, however, the French government ordered the letters burned and Voltaire persecuted.