> The continued relevance of these questions meant that thirty years later, in June 2020, YouGov were able to asked respondents the same questions, allowing us to discover how public opinion has changed in the intervening period. > Interestingly, the results reveal a fall in public awareness on the issue. In 2020, about half the population (51%) reported having heard about the proposals – though this figure seems likely to rise with the PM’s recent announcement. Back in 1990, the figure was a much higher 78%.

It goes on to list the coronavirus and Tiananmen as possible reasons; isn't the most obvious contributory factor that a lot of voters have been born since then, and it hasn't been on the national curriculum or often reported on?