Yeah. Though it's going to be difficult as hell, for my fic, with the Master telling it so therefore he's got to see it, without realising what's going on...

Oh! Perhaps spying on the Doctor and Jack through the CCTV or something. Putting them together and watching them, and listening to what they're saying aloud, but unaware that the Doctor's light hand on Jack's bare forearm is anything more than just a touch for comfort...