I agree with you, Martin, but I can't see any anvils in the first image (?). The grey cloud in the upper part of it looks more like a closer patch of Cu fra. So, imho again, that Cb hasn't reached tropopause at the time of image capture.
The top of a cb (cumulonimbus) cell always stops growing when it hits the tropopause, this when you will see the distinctive anvil flattening out along this ceiling.
Well, I just cannot stay away while other post here images of convective weather...
Here are two shots from last May, captured in the countryside not far from Poltava.
...A nice summer day (temperatures +20...+25C) with plenty of Cu, Cb clouds and several T-storms travelling in the neighbourhood...
This Cb was 10...15km away (actually, there was a good t-storm passing by, you can see the darkness below). My rough estimate of cloud's height is 7-8km, maybe higher - it was developing enormously quick. There is no anvil from this cloud, but those Cs clouds were possibly anvils from more distant Cb cells, so the tropopause was certainly above 10km there...
At the same time a similar freak was closer to me (to the right - E), possibly it was smaller than the more distant one. I remember, when we caught a bus several minutes later, it went east - and we appeared just under that cloud... heavy enough rain followed, along with a t-storm. But I guess it was very moderate comparative to the more distant one
