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 October and the most expensive month to fly is September. (Average prices, based on 237 datapoints.)
The best day to arrive at London is Wednesday and it would be best to avoid Saturday, as prices are on average 109.11% higher than on Wednesday. (Average prices, based on 257 datapoints.)
At London the most flights depart around 18:00. (Hourly flights, based on 270 datapoints.)