Bit of an update from my side – I went back to basics and came upon 2 sentences in that said that one could communicate with the conduit by using the linux commands if one installs cygwin or by using terra term or putty with ssh on port 22. I definitely missed this previously. So, as soon as the root@mtcdt:~# appeared after logging in I typed npm install node-red-my-new-node. This appeared to install successfully – at least there were no errors in the terminal displayed. I then also restarted node-red from the conduit UI.
However, my new nodes have not appeared in Node Red. Advice?