Finding the best cheap airfare to London is not very difficult if you know the places where you should look for it. You are more likely to get cheaper airfare if you have a flexible schedule. Asian airlines like Kuwait Air or Air India should be your first choice for this, provided you are not too picky for flying in these flights.
The Asian airlines usually sell the tickets with the help of consolidators. They fly via London. The US-London sector seats are usually not full because the travelers use their own country's airlines to book their tickets. So you can easily get a ticket to London in these flights and that too too at a reasonable rate.
You are likely to get even cheaper rates if you fly during the off season. You will pay less if you fly between these periods: mid Jan to March end or November to early December. This is because the traffic is less and that's the reason that the ticket prices are down. So plan your journey accordingly.
You can also plan your trip well in advance to get cheap airfare. You may get the cheapest tickets if you are lucky because these airlines give special rates to people who book early. Discounted rates are released from time to time by the airlines. To make sure that you do not miss out on these tickets, check the airlines sites regularly.
You can also quote a price on Priceline.com. The site will then contact the various airlines sites to see if anyone is willing to sell the ticket on the price quoted by you. However its drawback is that you can not refund the ticket. You have to go with it even if it does not meet your timings.
You can get cheap airfare if you start searching for it well in advance. However there's a hitch. You are likely to pay less if you buy your tickets 10 days in advance rather than buying them at the last minute. It's a misconception that last minute airfares are the cheapest. The best deals are actually available 6 months in advance. The tickets disappear quickly once they are available for sale.
You may not get the lowest airfare if you ask for it from an airline reservation desk. The best place to get cheap airfare is the internet. This is because there are no frills involved in online booking. You have to do everything by yourself. This also saves your time and the airlines too do not need to employ more people for selling tickets. So it's a good deal for everyone.
There are also some sites which will send you low fare alerts if you subscribe with them. So you should become a member of these sites. Who knows, you might end up getting a great deal.