I come to the UK for Christmas every year. I know that the roundtrip fare booked on, say, the Wednesday before Christmas might be $500 and the Thursday before $1500. There's a similar (but much smaller) jump up before Summer hols and again after. I don't usually get to make a trip in Spring, but as we are currently plotting world domination planning my move, I'm hoping to spend a couple weeks in May/June.
Can anybody tell me roughly when the fares jump? Is it a sudden, acute jump like at Christmas, or something more gradual? Is it a huge difference?