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 793 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 965 datapoints.)
At London the most flights depart around 18:00. (Hourly flights, based on 1370 datapoints.)
From London most of the flights depart to Frankfurt, second best connected from London is Amsterdam. (Daily flights, based on 143 datapoints.)