Actually, Pertwee's comedy cleaning lady comes in The Green Death near the end of his run, by which time the UNIT family has been built up enough for comic banter with Mike Yates: "I like your handbag!" Pertwee does have a weird 'comedy' moment in the shower in Spearhead, though. Sorry to be pedantic.

Anyway, I've never liked this story, or Donna, very much. I found this too story slight to really care about, although it seemed better than some of the previous season. I think by this stage I was enjoying the tenth Doctor's adventures in comic strip form in DWM much more than on TV, not least because I didn't have to imagine the extremes of Tennant's performance.