Warning: Spoilers ahead for Doctor Who season 15, episode 4, "Lucky Day."end of "Lucky Day," it would appear that Doctor Who was ready to put the mystery to rest.

However, if "Lucky Day" has cleared up this particular enigma, then it'd be rather underwhelming for such a big question about Belinda's first encounter with the Doctor. With Doctor Who's Disney era already boasting more than its fair share of underwhelming reveals, it would be a risky move for showrunner Russell T. Davies to do it again with Belinda. With any luck, the scene in "Lucky Day" is just one clue that will eventually lead to a larger unveiling of who told the Doctor about Belinda Chandra.

It Seems Like It Was Conrad Who Told The Fifteenth Doctor About Belinda

The Doctor hadn't yet met Belinda when he crossed paths with Conrad at the end of "Lucky Day"

When Jonah Hauer-King's Conrad Clark is temporarily liberated from prison at the end of "Lucky Day," he finds himself in the company of a scorned Fifteenth Doctor, who is furious about what Conrad did to Doctor Who's new UNIT team - but more importantly, his betrayal of Millie Gibson's Ruby Sunday. After Fifteen identifies Ruby as his friend, Conrad replies, "You've had plenty of friends. Have you met Belinda Chandra yet?" The Doctor's reply of "Who?" confirms that no, he hasn't. So, this is the first time Fifteen has heard the name, and it's from Conrad.

"I was told about you by someone. It's kind of a long story, and I've got to be careful about timelines. But he told me your name, like you would be important."

- The Doctor to Belinda in Doctor Who season 15, episode 1, "The Robot Revolution."

The scene takes place after the Conrad crossed paths with Belinda and Fifteen at the beginning of "Lucky Day," Hauer-King's character has an advantage over the Doctor in his respect, as he knows a little of what's to come for the Time Lord. This interaction at the end of "Lucky Day" could easily be what the Doctor is referencing in "The Robot Revolution."

Conrad Being The Answer Is A Bit Of An Anticlimax

There were better options for who told the Doctor about Belinda

Conrad is a great villain within the context of his debut episode, but against the backdrop of a more cosmic storyline, he doesn't really fit. For an incarcerated conspiracy theorist to be the character who set Doctor Who season 15 in motion is an okay idea on paper, but he doesn't feel pivotal enough to Belinda's larger arc for his place in the mystery to be justified. He knew almost nothing about Belinda other than her name and what she looked like.

Plus, Conrad didn't say Belinda's name as if she were particularly important, which is what the Doctor implied was the case during the exchange in "The Robot Revolution." Plus, if anything, Conrad just got lucky that day in 2007, when he first met the Doctor and Belinda. There's no deeper meaning behind Conrad knowing who she is, nor did he have reason to believe she was special. It could all add up, canonically speaking, but that doesn't necessarily mean it would be a satisfying reveal, which is what I've been expecting since Fifteen's cryptic explanation in the season 15 premiere.

Who Else Might've Told The Fifteenth Doctor About Belinda, If Not Conrad

My alternate contender is a very familiar face

At the moment, Conrad is my main suspect for the character who told the Doctor Belinda's name. The evidence in "Lucky Day" is quite strong, but not yet airtight. So, it's still possible that the Doctor started to look into Belinda after his conversation with Conrad, but only decided to go and find her after a conversation with someone else. If so, then I think another likely candidate could be Belinda's father. Although he hasn't yet appeared, Belinda has mentioned him several times, which could be a way of foreshadowing his debut.

Ultimately, it's up to Doctor Who season 15's final episodes to reveal the truth, but that doesn't stop me from speculating.

Fifteen's concerns about timelines could also be a clue, and not just because of his conversation with Conrad. Instead, Fifteen's future self, from the end of season 15, may have traveled back in time to set events in motion by telling his past self to go and find Belinda. It's one thing for the Doctor to interact with his own timeline, but it's probably far worse to allow too much information about that encounter to get out. Ultimately, it's up to Doctor Who season 15's final episodes to reveal the truth, but that doesn't stop me from speculating.