Both Alex Kingston and John Barrowman have said on more than one occasion that they would be more than willing to make a return to the Doctor Who universe. This is all well and good. Indeed, it's one of the benefits to the modern series that companions and friends don't necessarily have to be gone and forgotten forever once they leave the show (an honour previously reserved exclusively for the Brigadier). Also, having River or Jack meet up with the 12th Doctor could have some interesting things to say about the current era of the show, as they both are so emblematic of previous Doctors (11th and 9th, respectively) that their mere presence would open up a discussion of how this era contrasts to theirs. The problem however, is that this era is still figuring out what it wants to be when it grows up (see the previous entry about old adversaries). Having such a clear reminder of what previous incarnations grew into before this one has a chance to will only serve to underscore the fact that this era hasn't quite gelled yet. Don't get us wrong, though. It would be fascinating to see how Alex Kingston and Peter Capaldi would spark off each other. Just not this year, OK?