What I hadn't realised is that this seems to be all about iCloud data. I thought it was about messages. But it looks like messages are still end to end encrypted and can't be read. Not my area of expertise because I hardly use tech.
I think I have the answer now!
It might also include messages. The messages themselves are end to end encrypted. But if they are backed up to iCloud, then the level of encryption for those messages will depend on the encryption setting in iCloud. So my advice for any terrorists who can't live without the latest iPhone is to turn off iCloud.
