[Interest] Updated Debian packages or ppa for Qt 5.9+

[Hamish Moffatt]

Does anyone know of a repository for updated Qt packages for Debian 
stable (stretch / 9)?

I thought I remembered reading of one on this list not too long ago, but 
I checked the archives and can't find it now.


Debian 9 has only Qt 5.7. I'd like to get on 5.9 at least, and I would 
prefer to have deb packages rather than using the installer or building 
my own from source.


Thanks

Hamish