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 1078 datapoints.)
The best day to arrive at London is Tuesday and it would be best to avoid Thursday, as prices are on average 93.84% higher than on Tuesday. (Average prices, based on 351 datapoints.)
The cheapest airline flying to London is LOT Polish Airlines. They are 79% cheaper than Swiss Int Air Lines. (Average prices, based on 1130 datapoints.)
At London the most flights depart around 07:00. (Hourly flights, based on 1247 datapoints.)
From London it is on average the cheapest to fly to Paris and to Istanbul. (Average prices, based on 168 datapoints.)
From London most of the flights depart to Paris, second best connected from London is Doha. (Daily flights, based on 65 datapoints.)