Pretty sure i know the answer but cant find definitive yes/no.
Is there a way e.g. api call to make a page stored in google's amp cache to force it to get new copy of that page?
Editorial want to know when they update a page in cms that google gets updates too.
Yes, you can easily force the Google AMP Cache to update your AMP page:
The most effective way to update the version of any AMP document stored in the Google AMP Cache is to access that document using the AMP Cache URL format. The Google AMP Cache automatically requests the latest version of the AMP document from its origin and serves the updated version to the next user.
For example, to refresh http://example.com/amp_document.html, simply navigate to https://cdn.ampproject.org/c/example.com/amp_document.html.