Ever since she made her loud-mouthed debut at Coal Hill School, we've wondered just what impact Courtney might have on the show. Would she be just a real-life foil for Clara and Danny? Well, yes that's a given. But would she also become involved in the affairs of the Doctor? After last week's episode we wondered if one vomit-inducing trip on the TARDIS would be enough. Turns out the Doctor quite likes Courtney and is willing to let her accompany him in a trip to the moon. Surprisingly, Courtney has never veered into annoying territory. Certainly not Artie and Angie annoying. Capaldi's Doctor obviously has better judgement when letting kids venture onto his TARDIS than his predecessor. This week Courtney proved she made of sterner stuff, becoming the voice of reason when the debate raged over whether to kill the alien creature within the moon. Sure she had her moments of 'I'm bored', but she also portrayed a more mature, reasonable side that suggests another trip on the TARDIS might not be a bad thing. Given Clara's current anger with the Doctor, it's unclear whether he'll be making a trip to Coal Hill School again, or whether Clara will continue to travel with him. Perhaps there is potential for Courtney to become that replacement?