I was in Finance in Britain at the time.
He was the one who saved banks with unconditionally given public money, then turned around and put them in a special "hands-off" management structure where basically the bankers managed themselves.
Royal Bank Of Scotland did not restructure their Investment Banking operations for almost a decade and kept losing billions of pounds every year. I actually worked there for a bit during that period and they were spectacularly inefficient and chaotic compared to other Investment Banks I worked in and under no pressure at all to improve.
Oh and Zero Interest Rate Policy in the UK - that started under Gordon Brown too.
The 2008 Crash recovery was one of the slowest recoveries from a Financial Crash in History.
All this crap then led to Austerity (by then under the Tories), which in turn fed the mix of discontent and scapegoating of the EU that led to Brexit, which in turn put the UK in the sorry state it is today.
Gordon Brown did not repair even the British Economy, much less the World's.
I remember those claims back then already and they were complete total bollocks fed by a handful of opinion makers in British newspapers and New Labour politicians - as far as I know, not a single international Economist endorsed that idea that Gordon Brown saved the World's Economy: the whole thing was just one big circle jerk of New Labour politicians and supporters.
I think you've been watching too much BBC and reading too much The Guarding - they're the ones who invariably spin "Briton saves the world" stories out of British politicians swiping British problems under the carpet and leaving them for others to solve later.