Nope, this is a fresh install. Haven’t had anything else installed prior.
Tried installing libcec 3.0 again as you suggested:
E: Version '3.0.1-16' for 'rbp2-libcec-osmc' was not found
My sources.list:
deb http://ftp.debian.org/debian jessie main contrib non-free
deb http://ftp.debian.org/debian/ jessie-updates main contrib non-free
deb http://security.debian.org/ jessie/updates main contrib non-free
deb http://apt.osmc.tv jessie main