Britain is a major partner; but with its physics funds under pressure, it is unclear how much the UK can contribute.
Strangely enough, this is the one area in which the US has followed up on the necessity to invest in light source upgrades. The LCLS has sufficient funds to proceed, and the NSLS II facility is proceeding along as expected. But then again, these are in the Basic Energy Science (BES) division of the Dept. of Energy, which was not devastated by the recent budget cuts, unlike the HEP and Nuclear Physics divisions.