This screencap was taken from the 50th anniversary episode The Day Of The Doctor, just a random prop photo on the UNIT noticeboard full of companions, a completely non-canon mash-up of UNIT Captain Mike Yates and First Doctor Companion Sara Kingdom, Space Security Agent.
Come on, Big Finish, you know you want to explain this one. It's a new Sara Kingdom story, you know it makes sense.
Well, it doesn't and that the point. This is a mad combination of Third and First Doctor era characters but it would certainly be damn entertaining.