Even with Brexit, many people in the economic world still consider London the financial center of the world, which is why its session is taken so seriously. It has always been a center of trade, and the city itself has an economy that dwarfs entire European nations. London is hands-down considered the metric when it comes to European markets, which of course means a lot. Because of its strategic location, it is largely considered the center of international trade. This tradition is also historical, and hails back for centuries, even if New York has risen to essentially challenge its throne, in some respects.
It is still considered the forex capital of the world, as the city of a little over 3 million residents is still responsible for almost a third of all forex transactions in the entire world. That certainly is remarkable for one city.
Here is a table of London session pip ranges using past data:
One great thing about the London session is because of the increased liquidity, this might mean that there are lower pip spreads and transaction costs, which often means that there is quite an opportunity to trade here. Of course, for those who are looking for thin liquidity, that certainly is not the case here. This is widely considered the most volatile session, however, which might present the most opportunity for those who are trying to catch a bottom, or make a profitable swing trade.
This volatility tends to die down when traders go to eat lunch, right before the New York session, as well. The tightest spreads are, of course, with the majors, as is the case with most sessions. Because European news comes out at this time, this is certainly what should be focused on. Since the European market can then adversely affect the Asian markets, the trader would be smart to keep an eye on the yen, and check if the pairs such as EUR/JPY and GBP/JPY have any potential, even if the spread might be a little more precarious.