The opening premise that the country has declined since joining the Common Market is complete tosh.

Best decade? 60s

Met my missus. Free higher education and grants.
Sgt Peppers, Pet Sounds.
Millers in 2nd division (well, for some of it).
Contraceptive pill.
Mini skirts.
Respect for miners and steelworkers.
Labour government.
1966.
and so on.....