Cannot open recent Pages document "need newer version"
I am running Yosemite 10.10.3 on a 2012 Macbook pro.
I have the most recent Pages 5.5.3 I am aware of (the document was created on this machine and the software hasn't been updated since). I have a document saved in iCloud - created about ten days ago and when I try and open it I am faced with an error message - asking me to download a newer version 9n order to open the document - others on iCloud will download and open.
Having Googled, I have checked and the default for this document is the current version of Pages. I have removed the old 09 iWorks from the application menu so that only the latest version of Pages can be accessed and I still get the error.
Can anyone help please - this is a lot of work which is now inaccessible to me?
MacBook Pro (13-inch Mid 2012), OS X Yosemite (10.10.3), Pages v 5.5.3