The National Physical Laboratory (NPL) is the national measurement institute for the United Kingdom. NPL expertise in the fabrication and characterisation of GaAs-based semiconductor single-electron pumps. NPL also has access to Josephson voltage standards, quantum-Hall resistance standards and cryogenic current comparators. They work with the University of Cambridge on semiconductor device nanofabrication. NPL has developed a null-detector method for high-precision measurements of single-electron current sources and demonstrated 1 part in 106 accuracy in 2012. NPL are coordinating this project and will contribute to the development of GaAs-based pumps and high-accuracy measurements of GaAs pumps and Si pumps for universality tests.