From Travel Mole:
EasyJet signs deal for major expansion at Stansted
But I will quote two paragraphs direct:
But it is not certain that easyJet will take advantage of the deal's full potential, as it has also struck similar deals with Edinburgh and Gatwick airports since they were sold off by airports operator BAA.
An easyJet spokeswoman said: "It is too early to say. The deal gives us the framework to do so but we won't take decisions on capacity for next year for some months.
It would have been odd if EZY were not talking to the new management at STN. They are acting as a well-run commercial business, securing themselves as many options as possible in the south-east market. They seem keenest on Gatters at present - yields are highest there - but now they have the ability to play the other three bases off against eachother.
If a new aircraft order is forthcoming, they may make full use of their newly-negotiated capacity at STN. They could move 3 or 4 aircraft from LTN to STN, but moving established routes would seem like taking unnecessary commercial risks. Any capacity freed up at LTN would quickly be taken by other operators - perhaps that's a risk they don't want to take at their home base.