In the first instance, despite the great naval victory at Trafalgar on 21 October 1805, Napoleon achieved hegemony in Europe during 1806-1807 allowing him to introduce an economic blockade of British goods. It was, in sorts, Brexit Mark I. The only country that did not adhere, Portugal, was invaded and the Royal Family evacuated to Brazil under Royal Navy escort. With British goods barred from European markets, British policy makers looked to expand overseas trade. America was trying to remain neutral through an Embargo Act of 1807 which forbade trade with Britain and France, that left Latin America. Here, following the failure of initial hard military intervention, the British looked to open up markets it had been traditionally excluded from. Isolating Spanish and Portuguese colonies from Europe was one strategic effect of British naval power, but also crucial was Napoleon’s meddling in Iberia. The effect was to open up Latin American markets to British trade and expanding existing West Indies trade. British trade with America outside of the USA doubled in value from £7.8 million in 1805 to over £16 million by 1808. That compensated for the loss of trade with Europe and the United States. And it was British economic prosperity outside of Europe the provided the fiscal muscle to reengage with European politics by bankrolling the alliances of 1813-14 and 1815 that finally brought an end to the Napoleonic regime.
Article source: http://www.huffingtonpost.co.uk/martin-robson/brexit_b_12558626.html?utm_hp_ref=uk-politics&ir=UK+Politics