Drake
I don't see a thread on this-- not merely that No 6 is a kind-of-continuation of the Drake character from Danger Man, but where he's identified by name as "Drake."
Here's one: episode 16, "Once Upon a Time", at 18 min and 56 sec, No 2: "Report to my study in the morning, Drake!"
This might be the only time they were specific. Danger Man's ambiance drifts through episodes like "A, B & C" (that cheesy party) and "The Girl Who Was Death". But as far as I know, they never came right out about them being the same. Except here-- only, perhaps?