Having now correctly installed the libpq-dev package I now have all the Perl modules installed.

So, now starting the ledgersmb-starman.service appears  to be successful, BUT NOT SO, as it continually stops and tries a restart with a new process.
I managed to grab a screenshot of the error (attached).
HEAD- MEET WALL!!!
--
Howard.
--
When you want a computer system that works, just choose Linux;
When you want a computer system that works, just, choose Microsoft.