flybymike, after the event you are correct, unless an airprox results (unlikely if all the a/c talking to ATC in west lakes's scenario are taking a DS.)
What the bimbler would have managed to achieve is an increased workload for the ATCO, and a/c taking some potentially fairly violent (for want of a better word) manoeuvres to avoid a collision. I've seen similar happen at my unit. All this could have been avoided by the bimbler making two-way contact and agreeing a course of action.
As an aside, I may as well take this opportunity to point out to anyone flying in the SW that Newquay does have instrument approaches to runways 12 and 30 that are not marked on the chart.