In % terms the outcome of the 2016 referendum was close 52% leave and 48% remain. Very different to the referendum in 1975 where the vote was 67% remain and 33% leave.
However, in 1975 UK had only been a member for 2 years since 1973. So not a lot of history to review as to whether EU member ship was good or bad for the UK.
Also during the 1970s UK was battling with; oil crisis, strikes, huge inflation that lead to the winter of discontent in 1979. Possible that internal issues took peoples' eye off whether or not EU was good or bad.
1980s consisted of the Falklands war in 1982. Victory in 1983 GE by Thatcher. In 1984 and 1985 there was the NUM strike. Thatcher defeated the NUM which was previously considered unbeatable.
This paved the way for privatization of many National Companies, Telecom, Water, Utilities and even BP in 1987. Many ordinary persons in the street made quick overnight profits and it added to the feel good factor. Thatcher won again in 1987 because people felt good.
Money became more easy to borrow and increased home ownership. Property prices tripled during the 80s and by even more in London and the South East. Again it all added to the feel good factor. So again nobody looked at whether or not UK's membership of EU was good or bad because everyone felt great anyway.
Then come the 90s and the feel good factor begins to lose momentum. Recession in 1992 and interest rates touching 15% soon cooled things down. Conservatives won the 1992 election against the odds. However, Black Wednesday and UK's need to withdraw from the ERM cast doubt over conservatives ability to run the economy.
In 1997 labour win GE with a huge majority of seats even though the majority of the UK voted against labour. Remainder of the 90s was dominated by; death of Princess Diana in 1997, GFA passed in 1998, UK chooses not to use the Euro in 1999 and the build up to the millennium in 2000.
Early 2000s were dominated by; foot and mouth disease, 911 attack on USA in 2001 and 2003 invasion of Iraq.
So after 30 years of being in the EU from 1973 to 2003 was anybody taking any notice of whether UK's membership of EU was good or bad? Maybe not.
2004 ten more Countries join from Southern and Eastern Europe join the EU. Was this the beginning of problems and the increase of immigration? Take a look at the chart. Immigration increased massively under the Labour government long before 2004.
Then there was the famous note from Labour "there is no money left". However, the financial crisis was in 2007 and whoever was in power would have had to do some bailing out of the banks.
Before 2015 GE the PM, Cameron, promised to hold a referendum on EU membership if he won. He did and so a referendum was held in 2016 and the vote was to leave.
Impossible to say for certain, but based on the above the feel good factor of the 80s seems to disappear from early 90s. The point at which immigration began to rise rapidly.
Those two occurrences could be totally unrelated, but when things start to go wrong and people feel less happy it is always someone else's fault. Was immigration the easy scapegoat along the lines:
"everything was good up until immigration exploded"
The financial arguments about the economy, loss of jobs, weak currency, etc., presented by the remain supporters don't seem to have made much difference to those who support leave. So why are they standing their ground the remain supporters ask? How can they not see they will be worse off? Well maybe the vote to leave was superseded by considerations not connected with money. My best guess is that it was all about;
IMMIGRATION