In fairness to Cameron HE didn't promote ripping up the agreement. It was Leave who said that it didn't matter. Cameron was just arrogant in thinking that he'd win the ref and it therefore wouldn't be an issue.
Cameron called the ref to kill the tory redmeaters. However the problem hasn't been solved and the argument is still raging as hard as it was in 2016.
Cameron, Hunt and Cleverely are all One Nation Tories I believe.
Note from wiki:
The Conservative Party's 2010 general election manifesto contained a section on "One World Conservatism", including a commitment to spend 0.7% of national income on well-targeted aid. In 2006, Conservative Member of Parliament (MP) Andrew Tyrie published a pamphlet which claimed that party leader David Cameron was following the one-nationist path of Disraeli. Phillip Blond, a British political theorist who has had past connections with the Conservative Party, has proposed a renewed version of one-nation conservatism.
Cameron getting a recall in this context, isn't 'out there'.
Johnson and May both claimed to be One Nation Conservatives to try and retain votes, but never were. But both saw the importance of this sector of the Tory Vote and how important it was to the party.
According to this political philosophy, society should be allowed to develop in an organic way, rather than being engineered. It argues that members of society have obligations towards each other and particularly emphasises paternalism, meaning that those who are privileged and wealthy should pass on their benefits. It argues that this elite should work to reconcile the interests of all social classes, including labour and management, rather than identifying the good of society solely with the interests of the business class
https://en.wikipedia.org/wiki/One-nation_conservatism
This is much more in line with politics in the EU and at odds with the ultra libertarianism of Johnson and Truss. (And the US - particularly Trumpian politics). It actually is more in tune with the idea of the 'Northern Powerhouse' which was popular with Northern Voters than the actions of Johnson (Johnson's rhetoric was actually a ripped off plagerism of Andy Burnham! But his actions never reflected his words).
Its also much more in line with the tone of opinion polls. Ironically. There's not as much desire for libertarianism in a cost of living crisis - which was the desire of Tory Elites but not the population as a whole. Northern Johnson Voters aren't libertarians - they are hardworking blue collar workers who in times gone by probably would have been characterised by Methodist christian values of work and being idle being a sin. (Hence why austerity has/had its supporters) All of this is very much ironic. The Tory party problem is its been out of step with the public in recent years with the only thing it has had to offer has been an anti-immigration red meat policy. Arguably its not worked and arguably its been at the expense of the economy and has run its course. The protests at the weekend were the final straw. Its unsustainable - it risks civil unrest.
It really does highlight the internal war of the Conservative Party thats been going on since 2010 between One Nationers and RightWingnuter with UKIP sympathies, has REALLY never been resolved and Brexit hasn't resolved it at all.
I don't think Sunak will pull it off, but I do think there is a realisation that the Tory party has perhaps gone as far as it can with libertarianism and that throwing anti-immigration as the bait to hoodwink voters into libertarianism can't deliver.