Don't understestimate the powers of Queen Maydas to turn all shes touches into political shit. Would the vote be on exit, or on whether to accept the deal or go for a no-deal exit?
I would place the primary blame on Cameron. Theresa May has been surprisingly poor, but Cameron is easily one of the most useless PMs we've ever had.
-Goes to school at the elite Eton, whose annual fees are higher than the average household income of an entire English family.
-For his first job, becomes a researcher for the Tory party through his godfather, who was an MP.
-Does PPE in Oxford, where he joins the Bullingdon club. There he meets the club President, a man called "The Berserker" - Boris Johnson.
-Boris Johnson diplomatically insults his first foreign leader whilst in Oxford, by bringing clubbies to go smash up the student Radek Sikorski's room. Radek Sikorski becomes Poland's foreign minister.
-Got elected promising everyone an EU membership referendum. Later stated that he believed the UK leaving the EU would be the death of UK & Europe, which means he was willing to gamble destroying everyone in exchange for getting a job.
-But he was lying, as he tried chickening out of delivering the referendum. Didn't work since UKIP was a thing, and his voters promised to suicide vote the Tory party into irrelevance if he didn't deliver.
-Delivers referendum, using every dirty trick in the book to try and win. Sending project fear material to targeted voters, keeping pro-EU MPs from campaigning whilst he campaigned, using taxpayer money to outspend his own legal campaign limits. Deliberately stops the government from making plans to leave the EU in order to not encourage pro-UK MPs.
-Loses EU referendum anyways, now with no plan.
-Despite being the PM with the democratic mandate to carry through brexit, despite promising he would remain PM if he lost, quits like a bitch anyways. Democratic mandate lost, Tory MPs begin stabbing each other in an orgy of retarded intrigue.
-Boris nearly becomes PM until he is kamakazed by Michael Gove.
-Gove later goes on a nice holiday with George Osborne, David Cameron's personal friend and most powerful ally in government.
-Osborne takes over the London Evening Standard, the quality of the newspaper drops instantly as the paper switches focus from all of London to white liberals of the north.
-Theresa May cleanses the cabinet of all of Cameron's bois.
-Corbyn eats coups for breakfast.
-Theresa May embarks upon her own campaign of mistakes.
-EU watches in confusion, unsure what to do, because they aren't sure what the UK is doing (it's telling that the EU commissioner is surprised Theresa May is still in power).
-Farage joins Fox and LBC, UKIP implodes immediately.
-Boris makes a diplomatic insult every week.
-David Cameron later states that he was "slightly wrong" about Brexit killing us all, as we're doing "slight less bad" than he had predicted.
-David Cameron is today worth £50M.
In regards to the latter, the secondrendum would be on whatever keeps the UK in the EU longest