aaaand another update - for those who read in future facing similar/same issues.
Agent was running fine and was able to remotely trigger a package install on the client fine. Read about previous bugs and saw this 1135620 – yum install katello-agent is not updating katello-agent status in UI
Although old and not directly related to the setup, issuing ‘katello-package-upload’ fixes the problem and the UI now report katello agent is running and hopefeully will report ‘installable updates’ shortly.
Such a shame Katello relies heavily on a package that has been made obsolete in EL6,7
Means the ansible steps will be growing a fair bit in order to push this out to all clients.