Ah but you see, there was a reason. See there was this time lord right... No listen, the time lord was in fact Sherlock... This is a good idea right. Anyway Sherlock just so happened to regenerate right, but he managed to keep his appearance because... Well I haven't thought that far yet, but deus ex time lords and gallifrey solves everything right? THINK OF THE CHILDREN!!!

Toss ‘em down the plothole!