From most locations, the cheapest flights to London can be found during the month of March; however great deals can be found at other times.
Most flyers found that booking flight tickets 60 days in advance of their planned departure date is, on average, the best time to get cheap flights to London.
On average, the cheapest flights to London are found when departing on a Tuesday. Try to avoid departing on a Saturday, as this is usually the most expensive day.
On average you can find the best deals on plane tickets to London when looking for flights with noon departure times.