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 2409 datapoints.)
The best day to arrive at London is Tuesday and it would be best to avoid Thursday, as prices are on average 106.6% higher than on Tuesday. (Average prices, based on 268 datapoints.)
The cheapest airline flying to London is Aer Lingus. They are 91% cheaper than United Airlines. (Average prices, based on 2584 datapoints.)
At London the most flights depart around 18:00. (Hourly flights, based on 2966 datapoints.)
From London it is on average the cheapest to fly to Amsterdam and to Frankfurt. (Average prices, based on 260 datapoints.)
From London most of the flights depart to Frankfurt, second best connected from London is New York. (Daily flights, based on 137 datapoints.)