Queen Mary wore the QV regal circlet to her first parliament.
I believe that Queen Alexandra was the last to wear the QV small diamond crown.

I have read that when a new crown was needed for the coronation of Queen Elizabeth (QEQM) the QV small diamond crown was considered for dismantling to provide diamonds. Thank goodness that idea was rejected. The regal circlet was dismantled instead. It was George VI who then had the small crown sent to the Tower.