Having refreshed my ancient knowledge of the ANO, and leaving aside the practicalities of keeping a good lookout when flying a non-coupled ILS approach, I am still surprised that there is a view that ATC can, or should, provide anything other than advice to any aircraft flying in class G.
I wholeheartedly agree that it would be reasonable for a pilot to expect some form of protection when flying an instrument approach into a big airport, but as I read the ANO no such protection actually exists in law in this case - just like anyone else in that bit of airspace (notwithstanding the priority given by Rule 17) the pilot has to use see and avoid as his/her primary means of avoiding a collision.
Clearly this is unrealistic, which highlights again how iffy this whole concept is. Add in the liklihood that many private flyers will assume (perhaps wrongly) that any aircraft making an approach in class G, better than VMC minima, will be flying under VFR and there is an even greater liklihood of a problem (give way rules etc, where you shouldn't give way if you have the right of way unless a collision is likely - to give way when you shouldn't can increase the collision risk).
All very sad, but we can, perhaps, hope that this dreadful accident highlights what I think is a serious issue that needs to be addressed to prevent further deaths.
VP