nigeglib, I was at an Airbus meeting earlier this year; the fuel system specialists were discussing potential modifications to a system - and they raised the topic of the Nimrod's single wall AAR plumbing.
They were aghast that such a lash up introduced 25 years ago was still flying in this hard-worked aircraft. It would never be accepted in any Airbus aircraft, they commented.
Tuc - I totally agree with all you have said and echo your sentiments regarding the painstaking efforts of Tapper'sDad.