British elections have until recently been pitting American consultants from the same party against each other. In 2015, Jim Messina worked with the Conservative Party while David Axelrod consulted for Labour. But for the European Union referendum, U.S consultants were on the same team. Strategists ranging from Messina to digital consultant Ian Patrick Hines, worked for the Remain side, which suffered a historic 52-48 loss in Thursday’s vote.

The Vote Leave camp, meanwhile, “kept away from overseas consultants,” Matthew Elliott, chief executive of Leave, told C&E in an interview following the vote. “We put together a bespoke team and brought in different people from different agencies. Basically, we didn’t have any U.S. consultants working for us.”

Of course that didn’t necessarily make it easier to line up against Messina and company.

“We were fearful because he had so much success with the Conservative Party victory in 2015,” said Elliott. “He knew how to target and microtarget through social media in the U.K. He had developed all of the techniques for the 2015 general election. Also, we were staffing up our operation from scratch from last October to yesterday, so we had a very short space of time to actually build things up. It was formidable, but we felt that with the right team, and the right strategy we could do it.”

When the referendum question was set last September, Elliott said the Leave camp started off as underdogs.

“Not only were we facing the British establishment in the government, we also, in some ways, took on the world establishment because all these heads of government [including Obama] were coming out to say that Britain should remain in the E.U.,” he said. “It was quite a challenge to actually win this campaign with all the forces arrayed against us. At the end of the day, this was a people-versus-the-elite referendum. And the people were on our side.”

In an interview with C&E Friday, Elliott went into detail on how the Leave side pulled off its surprise victory.  

C&E: Did Messina’s Remain team do anything unexpected?

Elliott: I think they pretty much did the playbook that we thought they would. They basically tried to scare people into voting Remain. They did that effectively by deploying not only the U.K. treasury, but also getting the IMF, the OECD [Organization for Economic Co-operation and Development] and Obama to say how [terrible] it would be if you vote Leave. That was their best card, but they played it early and they played it hard. By the end, they were so over the top, I think it rebounded on them.

C&E: Do you think this is a victory of British over American-style campaign tactics?

Elliott: I don’t really. Both campaigns had a big social media strategy; spent a lot on ads. Did a lot of micro-targeting. We have learned a lot from you guys. The fact was when we got started we didn’t have all the resources to be able to bring on the Jim Messinas of the world onto this campaign so we used homegrown talent. But that’s not to say we can’t learn from the U.S.

One key difference: In the U.S. you have lots of ad spend on TV. You don’t have that in the U.K., so we developed a very good research and comms team, which was able to drive a lot of the media agenda in our favor. We worked very hard to get the national newspapers on our side so we could get our message across. 

C&E: Was this campaign about immigration?

Elliott: That was a big part because you have free movement across the E.U. and it’s a big concern to many ordinary blue-collar voters who have seen their wages suppressed. They haven’t gone up for the past 10 years. They’ve also seen over-stretched public services. That was a key factor and our key message was how we should take back control. That really resonated with people. And we talked about the £350 million the U.K. sends to the E.U. every week and how the U.K. government should spend that on our priorities in the U.K., such as the National Health Service.

C&E: How big was the campaign staff?

Elliott: It was all built on the Business for Britain campaign [which Elliott ran], which had five staff. It grew to 120 full-time staff by the end of it with 30,000 activists across the country. It scaled up very, very quickly to being [almost] a medium-sized political party for the U.K. Whether it was the voters or the activists, people who wanted to leave the E.U. were much more motivated to actually do stuff than those who wanted to remain.

C&E: What was the campaign’s main focus? 

Elliott: We put lots of time into the TV debates because we knew that lots of voters who were unsure would want to hear the arguments so we put a lot of prep time into that. Sadly, in the U.K. we can’t do TV ads so that wasn’t open to us. We did a big social media component. To build up our grassroots army, Facebook in particular was very important toward that. We put a lot of money into Facebook advertising and we found that our engagement rates were way beyond not only what the other side was doing, but also way beyond what the traditional parties were getting on social media.

C&E: The sides both had £7 million spending caps in the final 10 weeks of the campaign, how did the Leave camp allocate its resources?

Elliott: A third of that money went on social media advertising and the whole digital component. Then a third on salaries and a third on the ground war with things like posters.

Q&E: Some of the polling going into the vote had the sides in a statistical tie, did you go into the vote Thursday thinking you were going to win?

Elliott: We were always cautiously optimistic that if we went into referendum day 50-50, then we’d be able to win because our voters are much more likely to vote. The activists are much more enthusiastic. They’re more likely to help with a GOTV operation on polling day. We were fighting hard to remain level pegging.

Q&E: How did you identify your voters?

Elliott: We did lots of polling at the beginning to actually work out who our key demographics were [in order to identify] a cross-party alliance of people who wanted to leave, and then we built a whole model based on that. We made it cross-party from the start so it wasn’t just a populist UKIP-style [UK Independence Party] movement. 

Things are much more restrictive in the U.K. than in the U.S. in terms of the lists you can buy so we really set up everything from scratch. We worked out who the core vote were and who the swing vote would be and worked out how to target them online. But more importantly, we figured out which spokespeople would appeal to them and made sure they were [seeing them] on TV.

This victory has to be put down to the blue-collar voters who came out in droves for Vote Leave.