Earlier quoted context omitted.
The UK did not choose austerity: https://commonslibrary.parliament.uk/research-briefings/sn06... but still has worse growth than the US.
They most certainly did https://en.wikipedia.org/wiki/United_Kingdom_government_aust... What they didn't do, unlike PIGS, was also tough reforms which are paying back now https://www.reuters.com/breakingviews/flying-piigs-nations-s...
See here for international comparison of government spending as % of GDP (the second figure showing trends over time), UK is not an outlier:
https://www.imf.org/external/datamapper/exp@FPP/USA/GBR/CZE/...