The U.S. and mainland Europe might not want to see the U.K. leave the European Union (EU) but prominent voices in the pro-Brexit camp told CNBC that the country needed to put its own interests first.
The comments come after U.S. President Barack Obama warned over the weekend that Britain could risk being put at the "back of the queue" for any potential trade deals with the U.S.
His comments have not gone down well with some "Vote Leave" campaigners. David Owen, a former U.K. foreign secretary and founder of the Social Democratic Party, told CNBC that the euro zone "experiment" had brought disorder to the whole EU and that the U.K. should leave.
"They've (the euro zone) left the EU in disarray, it's s dysfunctional organization and, sadly, I have to say more in sorrow than in anger, that it's in British interests to get out now before there's a collapse."
Owen had been pro-European throughout his career until recently when he declared he was supporting the "Vote Leave" campaign group that says the U.K. would mean the country has more power over its own affairs.
"It's time we put the interests of our people, our jobs and our prosperity first and got out of a totally dysfunctional union that is going nowhere," he added.
This weekend, U.S. President Barack Obama said any unilateral trade deal between the U.K. and U.S. could take up to 10 years. Owen dismissed that time frame, however, saying that a trade deal could be arranged in as little as 10-12 months "if you have a president that wants to help you."
"I personally think that there's an old convention and it's not a bad convention that you stay out of each other's political (business). He's the first president ever to have come into an election in the U.K. and I have a feeling he will regret it."
The debate over whether to stay within or leave the EU has deeply divided the political and business community with two rival camps representing the "Vote Leave" and "Stronger In" campaigns. Prime Minister David Cameron is hoping U.K. voters will choose to remain in a reformed EU. He and other pro-EU campaigners said that the country is better-off trying to change the Union from within and that there are unknown risks if the U.K was to leave.
Several business leaders have dismissed that notion, however and one fund manager told CNBC on Monday that it would largely be a case of "business as usual" if the U.K. left the EU.
"Not much will change in the short-term, there will be some instability post the vote if we choose to leave," Howard Shore, Executive Chairman of Short Capital Group, told CNBC on Monday.
"Not least because if you're being told there will be instability, that's self-reinforcing but fundamentally, terms of trade in the short-term will remain the same while the government negotiates with Europeans and the rest of the world."
"It's not in the Europeans' interests to change anything anymore than it is in our interests. We've got to think of the long-term benefits of leaving," Shore said. "I'm saying that because we're such big net importers of particularly German goods, it's just in much of their interests to keep the terms of trade the same as ours."
Aside from the country's business interests, trade and impact of a potential Brexit could have on the country's financial services industry, a large part of the Brexit debate surrounds immigration and the U.K.'s ability to restrict the number of immigrants and, particularly, benefits for EU migrants.
Shore believed that a vote to leave would allow the U.K. to improve the quality of its foreign workforce rather than cause a "brain drain" of international talent as Remain campaigners fear.
"If we leave the EU we can set our immigration policy based on who we want, not whether you're from Europe, Africa or the Middle East but on whether we want you to come here. Why should we give a particular advantage to someone coming from Eastern Europe over the Middle East or Far East."