Hi Steve, Adrian and list, sorry for my delay in replying. As I suggested in my OP, there aren't currently 9.3 (or 9.4) packages for Wily in PGDG, that's why I was asking if whoever's responsible for these packages could flip the switch to build them. It would be ever so helpful.
You should be able to add the pgdg repository to your system and then install through apt as normal. Scroll down to the "PostgreSQL APT repository" section on this page:
We want to run 9.3 on the above distro, which comes with 9.4 as standard (in the distribution). However, we note that there are only 9.5 packages in the postgresql 15.10 repository. Can somebody flip the switch to build these? We really aren't ready to upgrade to 9.4 at the present time.