Bleating about its failed space program is laughable at best, considering even the Falklands War was a stretch.
The only thing Britain has going for it today is the City of London, a money-laundering haven.
Since 1940 the UK has contributed hugely to the world - from the NHS and modern welfare state to scientific discoveries, medicine, engineering, pioneering computing, music, literature, contemporary art...
I agree its current political situation and economy is a mess, but retain some perspective.
The Greeks and Italians still seem to frequently do it today, finding national self-esteem in their epic histories. The Spanish a lot less so.
It prompts me to consider what separates cultures that reboot and seek a new greatness even while having a strong history (eg China), and cultures that continue to perpetually drift on a former glory (eg Greece). China of course had the 'benefit' of hitting a particular low to reboot from (Mao era), with an extraordinary amount of space above to fill-in (a billion people to put to work starting from sub $200 GDP per capita in 1980).