How did Walsingham actually come back to life in Bill?

Bill, the movie, is supposed to take place in 1593, and the film includes the fan favourite character Sir Francis Walsingham. However, this is kind of a historical retcon of sorts as he actually died in 1590 as mentioned in the IMDb goofs section, which is 2 years before the movie's events. But also, this is kinda intentional as we hear characters in Bill constantly mention "Walsingham! I though you were dead!" throughout the movie. While it does make sense and is kinda funny, it did make me think the actual inside lore of the film to how he actually came back to life. Was it witchcraft of some sorts? The dark arts? Let me know in the comments down below.