The “strange, old book collector” from the Sherlock Holmes canon turns into the perverted purveyor of media in Sherlock S3E1, The Empty Hearse. Looking back at The Empty House, among the titles the book collector offers Watson are THE ORIGIN OF TREE WORSHIP, BRITISH BIRDS, and THE HOLY WAR…just like he titles of the, ahem, selections above!

I just love the canon connections in this show!