Google Oauth Error: redirect_uri_mismatch

I'm trying to use google Oauth 2 to authenticate with google calendar API for a web server running on AWS EC2.

When I generated the credentials I selected 'OAuth Client ID' and then 'Web Application'. For the Authorised redirect URIs I have entered:

http://ec2-XX-XX-XX-XXX.eu-west-1.compute.amazonaws.com (I've blanked out the IP of my EC2 instance). I have checked this is the correct URL that I want the callback to go to.

The link that is generated in the server logs is of the form:

https://accounts.google.com/o/oauth2/auth?access_type=offline&client_id=XXXXXXXXXXXX-XXXXXXXXXXXXXX.apps.googleusercontent.com&redirect_uri=http://localhost:47258/Callback&response_type=code&scope=https://www.googleapis.com/auth/calendar.readonly

When I follow the link I get the error 'Error: redirect_uri_mismatch'.

I've read this SO question and have checked that I am using HTTP and there is no trialing '/'

I suspect that the URL generated should not have 'localhost' in it but I've reset the client_secret.json several times and each time I restart tomcat with the new client secret I still get a link with localhost but just over a different port.

Locally, I had selected Credentials type of 'other' previously and was not given an option for the Authorised redirect URI. I did try this for the EC2 instance but this won't give me the control I want over the redirect URI and sends the redirect over localhost.