Fly from Boston to London for $892 round-trip, nonstop, including all taxes, on British Airways. If that strikes you as a tad high, keep in mind that recent fares to London for winter/spring haven't been much lower, and here we're talking about peak summer! See? Not bad at all!
We're not in the game of predicting fares, but it's safe to assume that a summer ticket to London won't get any lower.
For a look at all of our current fares, visit our fare page for London Heathrow.