Right on the GCHQ website it states: "In addition, we are also pleased to announce that GCHQ and MI5 are working with their US partners to further strengthen UK

Right on the GCHQ website it states: "In addition, we are also pleased to announce that GCHQ and MI5 are working with their US partners to further strengthen UK-US collaboration on cyber security ..." I think it is fair to say they all use the same tools!