The events must be unraveling in or around year 1895. Malcolm & Kali shoot a gun referred to as the prototype of a semi-automatic Mauser. The first such gun was designed by Mauser in 1895 and released to production in 1896.
When Vanessa is speaking with John Clare in the tunnels there is a poster for the Grande Guignol Theatre behind her. The Theatre was heavily portrayed in season 1 as the place John Clare, known as Caliban at the time, found his humanity. The Theatre was also the site of the final showdown between Vanessa and her company against the vampire and his brides.
The British Library does indeed hold one of the world's largest collections of pornography. It is called the Private Case and was largely accumulated from private bequests (the first was made in 1857), rather than the more usual routes of purchasing or copyright deposition. Unfortunately, the original collection has been lost over three quarters of its books and the L'Enfer (hell) collection of the Bibliotheque Nationale in Paris may now contain more.
However, the claim that the Vatican contains the world's largest is an urban legend according to both Snopes and the Straight Dope, its holdings in this department are rather modest. Instead that dubious honor goes to either the Kinsey Institute for Sex Research in Bloomington, Indiana or the Institute for the Advanced Study of Human Sexuality in San Francisco.
However, the claim that the Vatican contains the world's largest is an urban legend according to both Snopes and the Straight Dope, its holdings in this department are rather modest. Instead that dubious honor goes to either the Kinsey Institute for Sex Research in Bloomington, Indiana or the Institute for the Advanced Study of Human Sexuality in San Francisco.
The language used in the episode is a fictional amalgam of Aramaic, Ancient Greek, Latin, and an obscure Arabic dialect called (in phonetic English) "Kan Allah Musali-Algins". The language, Verbis Diabolo was created specifically for the show by David J. Peterson (creator of the "Dothraki" language in "Game of Thrones").
Billie Piper's character is named "Lily", by Victor Frankenstein. It is the second time a character played by Billie is named after a flower. She was "Rose" in Doctor Who.