Re: 707s on IT flights - BMA used them extensively circa 1982-3 to the usual Med and Canaries destinations.
211 seats due to all-Y config and a galley taken out.
I don't know what the economics were, but there was one dedicated reservations agent at Castle Don. who spent his time dealing with schedule changes, calling the trade and private passengers to tell them the flight times had been changed, sometimes significantly. I guess that the intention was to chop any weak rotations and keep the load factors way up by smart utilization.
With typical astuteness, Midland got out of this market when seat prices fell, and the "Boeings" (as we called them) were redeployed on ABC Canadian charters.