Sarah Jane Smith takes Rose aside; the Doctor turns back to the computer like he's invisible. "What do I do?" asks Rose, glancing at the Doctor. "Do I stay with him?" That's not what she's asking: she's asking about what happens next, and about what doesn't happen next, and what happens after that. It's the latter set of questions Sarah Jane answers: "Yes. Some things are worth getting your heart broken for." She embraces her young double, this lovely young ex-rival she's learned to love: "Find me...if you need to, one day. Find me." Rose gives her a small smile. (Never. Might as well join LINDA, about whom we'll be hearing a goddamn earful down the road. No matter how many secrets they both know, they're still personal. What's sadder than one ex-Companion? Two of them. What's sadder than that? Becoming an ex-Companion before you're thirty, and hanging out with an old journalist and her secret talking dog. I'd die first. Find myself on the other side of Hell from that. Or, I don't know, like, Norway or something. Don't even give me your number, Sarah Jane!)
The Doctor holds open the doors for Sarah Jane, who steps out from the TARDIS for the last time. They stand in the sun, for their last goodbye. It's too bright. (And in the air you can hear a slower, sadder "Song For Ten." And if it wasn't instrumental, you could hear a man singing: "'Cause I followed my star/ And that's what you are/ I've had a merry time with you/ I wish today was just like every other day...") "It's daft," says Sarah Jane, with a smile, "but I haven't ever thanked you for that time, and like I said -- I wouldn't have missed it for the world." The Doctor smiles at her and makes assumptions: "Something to tell the grandkids." "Oh," she smiles, "I think it'll be someone else's grandkids now." That throws him off. "Right. Yes, sorry -- I didn't get a chance to ask. You haven't...there hasn't been anyone...? You know...?" (To her, perpetual maidenhood, And unto me no second friend.) "Well," she smiles sweetly. "There was this one guy. I traveled with him for a while. But he was a tough act to follow." The Doctor smiles back at her with all the love in the world; they wish today was like their days before. "Goodbye, Doctor," says Sarah Jane, and he jumps in with his clarion call: "Oh, it's not goodbye..." She tries to explain Season 2 to him (again): "Say it, please. This time. Say it." And he looks into her eyes, respectfully, sad and shining, and he says this: "Goodbye. My Sarah Jane."