A Discovery of Witches casts The Last Kingdom star for season three

"I’m really excited to be joining the excellent cast of A Discovery Of Witches," Regbo told RadioTimes.com. "Jack is a wicked character and it was great fun bringing him to life."

In the books, Jack is presented as an orphan child adopted by lead characters Matthew and Diana (Matthew Goode and Teresa Palmer) when they’re transported back to Elizabethan London – however, once they return to the present day he is left in the care of others.

As noted, some of Jack's storyline was already laid out in the recently-aired second season of A Discovery of Witches, and it’s expected that season three – which is based on The Book of Life, the third novel of Deborah Harkness’ All Soul’s trilogy – will explore Jack’s relationship with his family further.

Best known for his two-season stint in Netflix historical drama The Last Kingdom (where he played Lord of Mercia Æthelred), Regbo has also appeared in Sharpe’s Challenge, Sky’s 2011 series Treasure Island (where he played the central role of Jim Hawkins), the CW series Reign and Medici: Masters of Florence.

On the silver screen he has twice played a younger version of Albus Dumbledore (specifically in 2010’s Harry Potter and the Deathly Hallows Part 1 and 2018’s Fantastic Beasts: The Crimes of Grindelwald) and also appeared in films including One Day, Glorious 39 and Mr. Nobody.

As for when fans will see Regbo in action as the older version of Jack, well, it’s currently unclear, with Sky not yet officially confirming when we’ll return for the concluding part of the A Discovery of Witches story. Hopefully, it won’t be the two-year wait they had to endure between seasons one and two…

A Discovery of Witches S1 & 2 are available to watch now on Sky and NOW TV, with series 3 coming soon. Want something else to watch? Check out our full TV Guide.