Please be aware that New York and London has multiple airports and that these results are for all airports serving the city.
The best month to fly between New York and London is September and the most expensive month to fly is January. (Average prices, based on 400 datapoints.)
The cheapest airline flying from New York to London is Virgin Atlantic. They are 53% cheaper than British Airways. (Average prices, based on 416 datapoints.)
The best time to fly is at around 7. (Average prices, based on 465 datapoints.)