Warning: Spoilers ahead for Doctor Who season 14, episode 7, "The Legend of Ruby Sunday."

Summary

• UNIT's scientific advisor in "The Legend of Ruby Sunday" is a temporary replacement while Shirley is away in Geneva.
• Thirteen-year-old genius Morris is introduced as a stand-in for Shirley, but her return is confirmed for future Doctor Who episodes.
• Shirley's pivotal role in the Whoniverse's future hints at more UNIT stories, possibly leading to a spinoff show featuring key characters.

Doctor Who's UNIT dates back to the show's classic era, and the organization seems to have a bigger part to play than usual in Russell T Davies' second stint as showrunner. Since returning in the Doctor Who 60th-anniversary specials, UNIT has been proven to consist of faces old and new. This is a trend that continues in the penultimate episode of Doctor Who season 14.

Ruth Madely first played Shirley in "The Star Beast," and last appeared in "The Giggle." So, her appearances bookend David Tennant's anniversary trilogy. "The Legend of Ruby Sunday" is the first meaningful return of UNIT since "The Giggle." However, the fact she's been replaced with a new science advisor isn't explained during the episode. Thankfully, she will return at a later point in Doctor Who's Disney era.

Morris Is A Temporary Replacement For Shirley Anne Bingham In Doctor Who

RTD has confirmed Shirley is out of the country during "The Legend of Ruby Sunday"

UNIT's scientific advisor in "The Legend of Ruby Sunday" is Lenny Rush's Morris Gibbons. The thirteen-year-old genius is incredibly intelligent, "Thanks to a ing asteroid." While he is a more-than-capable replacement for Shirley, Russell T Davies has confirmed that Morris is only a stand-in for Madely's Doctor Who character. Speaking with Doctor Who Magazine (via Radio Times), Davies explained that Morris is there, "While [Shirley's] in Geneva."

There was no mention of Shirley heading to Geneva during her last Doctor Who appearance, so the plot development comes somewhat out of the blue.

There was no mention of Shirley heading to Geneva during her last Doctor Who appearance, so the plot development comes somewhat out of the blue. Ruth Madely recently appeared in an episode of Disney+'s Renegade Nell season 1, portraying Mrs. Miller in episode 7, "Stop Printing This Muck." So, it's possible that she was unavailable to return to Doctor Who because of a scheduling conflict. However, this isn't confirmed. Regardless, Lenny Rush's Morris Gibbons does a great job filling in.

Shirley Will Return As Doctor Who's Scientific Advisor

A Doctor Who producer confirms Madely's importance to the future of Doctor Who

The commentary track for "The Giggle" confirms that Shirley will be a key Doctor Who character going forward. Also speaking with Doctor Who Magazine, returning producer Phil Collinson described Madely's role during the 60th-anniversary as "All too brief," and confirmed that there will be, "Lots more of Shirley to come, as she plays an integral role in the new Whoniverse."

As a UNIT employee, the promise of more appearances from Shirley means the fictitious organization will continue to have a major role in the show's future. In fact, with rumors swirling of a UNIT spinoff show, Shirley could be appearing in the Doctor Who universe far more often. If a UNIT spinoff does happen, then there could even be room for Lenny Rush's Doctor Who character to remain as a regular contributor.

Source: Radio Times