The seat maps were almost empty for both 777's in this timeframe. No reason for CO to fly to empty 777's from IAH-LHR.

Consolidating the flights makes sense - but I would prefer the later flight CO4. Looks like CO has already merged the seats on the two flights - so if you were on CO4 - recheck your seat plus new connection.

Maybe there is a time factor in cancelling a flight to not loose the slot.