OK, the council rang me there. Had a great chat with them.
The Chinook and Strikemaster etc were not cancelled as such, they had a provisional list with a number of displays and a final decision was made in June of which would display. Those that were 'cancelled' as such were not actually confirmed as booked but just on a shortlist and had been contacted regarding availability on the date, provisional booking but not confirmed one it seems . As for the RAF, they were applied for and allocated Chinook, however it didn't make the final flight programme due to budget.