Please be aware that London has multiple airports and that these results are for all airports serving the city.
The best month to fly between London and Amsterdam is November and the most expensive month to fly is August. (Average prices, based on 1824 datapoints.)
The best day to arrive at London is Sunday and it would be best to avoid Monday, as prices are on average 41.7% higher than on Sunday. (Average prices, based on 395 datapoints.)
The cheapest airline flying from London to Amsterdam is KLM. They are 15% cheaper than British Airways. (Average prices, based on 1838 datapoints.)
The best time to fly is at around 7. (Average prices, based on 2451 datapoints.)