I will be taking the Best of England tour beginning in late September, and have been somewhat anxious about airfares. Fares on major airlines for my route MSP to/from LON (and probably most others as well) have been quite high ($1100 or so RT) for many weeks, after being much lower in Jan-Feb when I was considering this trip. However, starting yesterday there has been a significant drop in airfares. I booked a flight for $683 r/t on Delta, lower than fares to Europe that I have paid in past years. Some fares on AA and Delta today are even lower. This doubtless does not apply to all dates, routes and airlines, but now might be a good time to shop for your flights!
-Ben