The Future Internet faces many challenges for new Internet architectures, protocols and services requiring early experimentation and testing in large-scale environments. Furthermore, the complexity of the software and technologies running on the Future Internet will require more innovative and different approaches to the testing process. This paper examines these requirements and challenges and demonstrates how they are dealt with in the Telecommunications Software and Systems Group using a case study of the Future Internet project; PERIMETER. Details of the testing and experimental methodologies and the role of testbed activities involved in this Quality of Experience network mobility project to develop and adapt to the needs of the Future Internet are provided. The paper concludes with observations of the further developments and innovations required to achieve an end-to-end solution for experimental testing in PERIMETER, and more generally for other Future Internet projects.