It's where it is squashed between battens and the rafters that I am
especially sceptical, and if that does not work, there is quite a bit
of cold bridging.

It works a lot better for cold bridging than celotex only between rafters,
which is a very common method.

Obviously, the Super 9 will be a lot worse performing in those areas than in
free areas. However, they won't be too bad. Remember also, that these
bridging spots are just that, spots. They aren't entire lines, as the
battening runs perpendicular to the rafters and the bridging spots only
occur where they cross. The lines from the joist and battens will be
slightly compressed on one side, but will reach the majority of their full
performance.

Christian.