Please be aware that London has multiple airports and that these results are only for City airport.
The best month to arrive at London is December and the most expensive month to fly is February. (Average prices, based on 895 datapoints.)
The best day to arrive at London is Thursday and it would be best to avoid Sunday, as prices are on average 140.29% higher than on Thursday. (Average prices, based on 923 datapoints.)
At London the most flights depart around 10:00. (Hourly flights, based on 992 datapoints.)