Please be aware that London has multiple airports and that these results are only for Heathrow Airport.
The best month to arrive at London is November 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 69.44% higher than on Wednesday. (Average prices, based on 255 datapoints.)
The cheapest airline flying to London is Icelandair. They are 66% cheaper than Lufthansa. (Average prices, based on 491 datapoints.)
At London the most flights depart around 18:00. (Hourly flights, based on 914 datapoints.)
From London it is on average the cheapest to fly to Amsterdam and to Copenhagen. (Average prices, based on 180 datapoints.)
From London most of the flights depart to Frankfurt, second best connected from London is Madrid. (Daily flights, based on 148 datapoints.)