The question is well made. London to Edinburgh / Glasgow is a short and busy sector. If you are doing your job properly there is not enough time to go back for a chat, possibly a quick pee and that's it. Certainly the Captain should be at the controls during such a busy sector to verify ATC calls with his F/O.
I expect the F/O was getting quite worried and was probably considering dinging the call button to ask if there was any chance of the Captain comimg back!