Whoever ensured the referendum was in the Tory election manifesto certainly was planning on Brexit happening.

You don't pay millions in to Tory funds, employ MPs and give pensions to ex-MPs and not get your way.

Whose plan? Cameron's plan for sure, but it's not all that far fetched to believe he was ill advised and manipulated by his party (a lot of Eurosceptics in the Tory party). Ever watched Yes Minister? I know it's satire, but it's more than believable.

The leading faces of the Brexit movement--people like Boris Johnston or Nigel Farage--were completely caught off-guard by the victory. Cameron's decision to resign immediately after the referendum loss also meant that the Brexit negotiations would be completely owned by the Brexiteers, as they ran out of people who could be blamed if/when things go south.

What was desired by these leading anti-EU folks was not a victory, but a very close loss. They get to keep blaming the EU for every problem (useful, when the biggest gripe--immigration--was entirely under the control of the UK, not the EU). They get to demonstrate that they have too much support to be ignored, but they don't have the responsibility of actually enacting the agenda.