Positive progress, I'm updating incase anyone else comes this way: today I installed a fresh copy of linux Ubuntu desktop (18 LTS) and found the following:
./metashape.sh --server --control 1.2.3.4 --dispatch 1.2.3.4 -platform offscreen
...: error while loading shared libraries: libquadmath.so.0: cannot open shared object file: No such file or directory
The solution was to run:
sudo apt-get install build-essential
(why ubuntu doesn't have this installed as default along with a load of other essencial stuff like ssh server, screen and liklely a bunch of other stuff I havn't failed to stumble on yet, is beyond me)
This still ahsn't fixed the initial problem, which I am still working on.