This is nothing to do with ATC.
It is a failure of visual separation in Class G airspace, assisted by the departing aircraft (an RV) climbing enthusiastically to circuit height on a tight circuit.
ATC don't have eyes on the back of their heads, and separation of VFR traffic is not their job.
Quite correct in the second two paragraphs, but I would take issue with the first statement - it
needs to be a whole lot to do with ATC, if not as practised now, then in the future (and indeed to do with acceptable procedures at non-ATC aerodromes). For example, joining procedures when the circuit is active (direct crosswind join or not?), and more specific requirements about how and when traffic information is passed (and possibly updated) are examples of how this sort of incident needs to be followed up from an ATC perspective and procedures improved.
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