Using ghost directly on port 80

I am setting up a new latest version ghost install on a google cloud vm. Port 80 is open on the vm and cloud firewall. When i installed ghost i told it my domain name url and port 80. At installation time it configured itself on port 1024 per the config file anyway. It starts on port 1024 no problem but that is useless to me as i want it on port 80. I changed the configuration to port 80 and now ghost refuses to start telling me port 80 is in use. I have run a typical netstat | grep 80 and verified that no other process is using port 80.

All advice appreciated. The reason i am running directly on port 80 is i want to use a low power vm and when i add nginx the vm becomes unreliable over time. This is a low scale initial content creation rig.

I hope somebody can help.