To break the figures down
Of those who voted Leave in the 2016 referendum:
15% now think it was wrong to Leave, 10% now don't know. (Just?) 75% still think it was right.
6% of Remain Voters now think it was right to leave and 4% don't know.
Of those who voted Tory in the 2019 GE:
71% think it was right, 22% think it was wrong, 7% don't know.
Of those who still intend to vote Conservative:
75% think it was right, 19% think it was wrong and 6% don't know.
I wonder if that means 3-4% have been put off voting Tory because of Brexit now?
The over 65's are still 59% think it was right to leave, 37% wrong.
In 2016 it was 61:39 of those who voted, so not much change in that demographic, which is almost 1/4 of the voting population and they have an 80% turnout. The over 65's constitute 30% of the voting public.
It is unlikely that the EU will welcome the UK back with open arms until there is a consistent period of polling that shows significant support for EU membership, so, unless there are some very cold winters and the energy crisis is prolonged, it would seem like it needs a good 10 years before rejoin is on the table, on the basis the gap needs another 5 years to widen more and then 5 years to show we aren't going to change our minds like a flighty teenager.
Starmer's approach is pragmatic. Say we aren't rejoining, since it's not going to happen for a while anyway, while all time put everything in place to make it possible with the added benefit of mitigating the damage.