Thank you. For 18a Sin people want to commit I put EVIL instead of ENVY and I needed the V for 19d.
8d. Doctor stayed with multinational organisation, initially, not firm(8). I have UNSTEADY - anagram of STAYED + UN. Where does the Doctor come in?
26a Circle added to section of plane, for instance, as emblem(4) L?G? LOGO but where's the plane come in.