That might be a rumour in Freetown, but it isn't one in Luton.
Monarch have a smart commercial department and rarely do anything that isn't paid for up front.
This contract was scheduled to end last year but was extended over the winter. I understand that the 757 is more profitably employed on European bucket and spade routes over the summer. The SNA config meant that it was only being utilized on two flights a week on that contract and was substituting on some smaller airbus routes at other times.
The contract was mutually beneficial and the customer seemed happy.
