This is the first episode of a four-part story commonly known as "The Massacre of St. Bartholomew's Eve". The BBC destroyed all episodes at some point between 1972 and 1978.
Anne Chaplet was considered to become a main companion. As with Katarina, it was decided that her origins made her less than ideal for viewer identification.
Donald Tosh actually wrote most of the serial himself after the script delivered by John Lucarotti was considered to be too far from the original storyline. Lucarotti was reportedly so outraged by the changes that he demanded his name be removed from the credits. There are conflicting accounts as to whether or not this request was enacted or rescinded.
This episode was wiped by the BBC and no copy of it is known to exist.
Peter Purves has stated this as his favourite story from his time on the series. He called it "a great script and a wonderful opportunity for me to show what I could do". He added: "It breaks my heart that, although the full original audio exists, not a frame of the actual show remains."