Horn 1: eb1 - bb2
Horn 2: d1 - bb2
Horn 3: f - f2
Horn 4: d - bb1
Percy Aldridge Grainger (1882-1961) was an Australian composer and pianist, world famous for his many songs and orchestral works. Colonial song is a sentimental piece (listen to another rendition), and this translated very well to horn quartet with tuba.
With the addition of the tuba, all the horn parts are written in treble clef, even though quite a few leger lines are required in the 4th part. The key chosen is E flat, a darker and mellower key than most, which suits the mood of the piece well. It also helps with the range, as the highest note (quite often the tonic, as is in this case) is a bb2 in horns 1 and 3.
There are many subtle tempo and dynamic changes in the parts, without doubt to come close to the free feeling this work requires. The only downside to this otherwise excellent arrangement is that it is currently not commercially available.