Recent companions of the Doctor haven't only been white and basically middle class - they've been young, too. Not since the days of Wilf or Brian Williams have fans seen anyone possessed of a certain degree of maturity helping out the Doctor on his travels. A good cure for that ailment would be Evelyn Smythe. Listeners of Big Finish's audios first heard Evelyn in the Marian Conspiracy alongside the Sixth Doctor in which her love for all things history led to her travelling in time to witness the past first hand. Her eloquent barbs and rejoinders made her the perfect match for Colin Baker's externally acerbic incarnation and it's easy to imagine Evelyn giving Peter Capaldi's Doctor the same treatment. It's also very easy to imagine how the Twelfth Doctor would give Evelyn a hard time for her lack of physical ability given how much older he is than her. Since the remainder of Evelyn's life is described in the audios, her inclusion in on screen Doctor Who would require a "reboot" of the character, ditching, at least, the story in which she died. This retcon would be worth it just to see Evelyn sparring with Capaldi's Doctor - and winning. Fans needn't worry about messing up Evelyn's continuity, either - it's already been mucked up with her appearance in the novel Instruments of Darkness flat out contradicting her audio adventures.