Temporary asp.net (C#) developer

We are currently developing a new online gambling application in asp.net (C#). We have a working prototype and need a junior/intermediate developer to add experimental features to it as per our directions. These game features will then be submitted to user trials for concept validation. There is no up-front specification for this work, it will be agile in nature, as we try out new game features/concepts and receive feedback from our user trials. Looking for a developer with asp.net (C#) skills and ajax that is willing to work on a flexible basis as described above. South Bucks, Berks, London area prefered so can meet in person once project is underway if necessary. Ideal applicants will have a small portfolio of previous work - these can be student projects, etc. Expected duration of this project is 1-2 months.