First, I wanted to thank contributors to this thread for their helpful & incredibly timely responses!

My flight - BA2794 from LGW on 25/06 was delayed from 13:35 scheduled departure. It was originally due to arrive in Antalya at 20:00, but arrived at 23:06.
Crew onboard stated that the delay was due to a previous crew member not being able to operate the flight and therefore another was taken off of standby to fill in, but needed to fulfill his rest period before he could operate the flight.
BA have given ATC regs as the reason when I filled in their form for compensation.
I have seen in a recent reply that the aircraft used for BA2794 in a more recent flight is undergoing maintenance due to a tech fault.

Could I ask for more info about the delay for BA2794 on the 25th of June please?

Many thanks in advance!