I don't know exactly why they decided to land at Manchester or what ever airport but from what I have been able to pick up they had an issue getting fuel out of one tank so did it as a precaution. Someone said they had 16,000 pounds on landing. I have made decisions in my career I am sure others would find fault with but I still would do the same again. One situation usually has about three solutions, all of which would work just fine. I just don't like second guessing another pilot's actions when they were there and had over 12 hours to talk with their people and come out with a solution that worked just fine. By the time they left Gander airspace they should have been at a weight that another engine loss would not be that critical. We obviously don't worry about losing the second engine on our two engine aircraft or we wouldn't have 180 minute ETOPS