[Spencer]

They're far from the only broadcaster to do this with important interviews. The massive triple logo-ing from ITV with the partygate photographs spring to mind. It's probably primarily for the online clips to make sure it's on-screen when/if other broadcasters show it.

Also I presume the version used by other broadcasters won’t have the standard BBC News lower thirds, so it makes sense to include another logo to promote it as a BBC exclusive.

Even if they did include the straps at the bottom, they could easily get overlaid by other channels’ lower thirds, or cropped out.

Personally I think it’d look better in the top right or left hand corner, but still, I’ll take that effort over some international channels who plaster large, moving watermarks across the entire screen.