We had a Notam'd aerobatics competition yesterday at Little Gransden.
Three aircraft flew through the overhead in the middle of our aerobatic box at between 1500 and 2500 ft. None of them responded to calls on the Little Gransden frequency. We had to stop 2 flights and delay a 3rd because of them. They didn't even notice an aircraft doing aerobatics!
We normally get 2 or 3 doing this at a competition.
ZA