However, US President Barack Obama's remarks that Britain would find itself at the "back of the queue" when drawing up any potential post-Brexit trade deals with the US has also put the focus on Transatlantic commerce.

It is not the first time the US has threatened dire trade consequences should the UK vote to leave the EU on 23 June.

Last year, US trade representative Michael Froman warned that if the UK left the EU it would face the same tariffs and trade barriers as other non-EU countries such as China, or Brazil or India.

The tariffs which UK exporters pay (as a company based in an EU member country) on goods sent to the US are at present relatively low.

Imports and exports

The heightening of the trade rhetoric seems curious when one examines the current mutually-beneficial trading relationship between the UK and US.

While the EU bloc of nations is the UK's largest export market, that is a large territory comprising another 27 countries.