With respect to OP, the hyperbole detracts from the sympathy vote.

CX251 leaves at 2355 not 2300 as you seem to conveniently misstate. In other words the time difference is 1 hour 5 mins not 2 hours.

CX251 is usually the busier of the 2 late night flights as it arrives in LHR earlier and customs queues are shorter because of fewer arrivals at 5am as opposed to 6:20am, probably the reason it was full earlier - you are probably not the only misconnect on the CX/KA network sorry to say.