When? Which source? Another unbacked claim! I understand why you don't want to cite your sources! 😀
https://www.imf.org/external/datamapper/PCPIPCH@WEO/WEOWORLD/GBR/USA
On the other hand, for the last four published quarters, UK GDP growth 0.2%, USA 3% (×15)
https://commonslibrary.parliament.uk/research-briefings/sn02784/