I've a similar situation coming back from YYC in October. Was a 4 hour wait in LHR, but they've cancelled the 6pm LHR-MAN and put us on the 9pm instead. Will probably get the train home instead of flying, as will be home before 9pm. Am hoping that in the next couple of months they'll add another flight back in (I seem to remember reading that the next lot of flight changes are in March) as currently the flights LHR-MAN on a Saturday are 2pm and then 9pm.

T