Muse

An important character in this story is a girl who has worked as a model for an artist named Pickman. "Pickman's Model" is the title of a famous horror story by H.P. Lovecraft.

When Endeavour searches the glider, it has the registration G-AWTP. UK gliders didn't carry G- registrations until the 2000s. In 1968 they had BGA numbers.

In the closing credits after the actors' names have cycled through, certain letters of the crew's names are colored red. In order, these red letters spell out "Artemisia Gentileschi," the name of the notable female painter of "Judith and Holofernes," which is directly referenced in this episode. Artemisia Gentileschi was raped by one of her father's associates, who then refused to marry her. Gentileschi's father brought the associate to court, and although the man was found guilty and banished from Rome, the order was never enforced. Artemisia Gentileschi later painted three variations on the Judith and Holofernes story. It is widely accepted that she was expressing her desire to punish the man who raped her through the subject of these paintings.

References The Saint (1962)