I was thinking of this scene:
https://www.youtube.com/watch?v=YOW1Wjb_oEI
Though I have to admit the reason I think of him when it comes to doing accents is his American accent that's supposed to be NorCal but sounds like it's everywhere else at the same time.
may i ask that you clarify this point?
tennant made a personal choice NOT to use his native/normal scottish accent for Dr. Who. he discusses this with Jodie Whittaker (also someone with quite a strong native accent) in an episode of his podcast, he TL;dr said it didn't feel quite right for him to use his native accent for the role [1].
whenever tennant does TV "as himself" (for example the voiceovers he has done for various shows or charity events like comic relief etc) he uses his own/native accent, is he doing this for laughs/jokes? surely he is doing them with a scottish accent because that is actually his literal normal voice?
[1] https://podcasts.apple.com/gb/podcast/jodie-whittaker/id1450...