Was the C340 overtaking the C152 or did the C152 cut in front of the C340 on final... depending on how you see it one or the other was right, the other was wrong. Doesn't matter now when the collision is a fact. Some active coordination, instead of just position reports, would have been appropriate. Especially if you're intending to approach a GA field at 180 kts. Personally I think the C340 approach was madness...