Here are the top four which will be battling to maintain a free trade deal with the UK as much of their business depends on British customers.
All of them are from two of the EU’s largest economies, Germany and France, whose leaders have been fairly frosty towards the UK since it voted to leave the bloc last June.
However, politics and business do not always agree, with many EU countries not wishing to have tariffs placed upon them thanks to EU bosses intent on punishing the UK – and inadvertently European businesses.
French company Total oil and gas is the third largest European company by revenue and is extremely keen to keep its free trade deal with the UK.
Most well-known for its petrol stations, Total has an overall revenue of £172,662million and is only preceded by Royal Dutch Shell and BP in both the UK and Europe.
Total, also known as Elf in Britain, has serious investment in the UK as it was the first major oil and gas firm to acquire exploration rights for shale gas in Britain in January 2014.
The company bought a 40 per cent interest in two shale gas areas in Gainsborough for just over £43m and will not want to lose that innovative investment.
German automobile company Volkswagen is Europe’s fourth largest company and the biggest car company across the continent by far.
VW relies on Britain, where it is the third largest automobile company after British cars Ford and Vauxhall.
In 2016 a total of 129,044 Volkswagen cars were registered in the UK, meaning it nabbed 7.87 per cent of the market.
The VW Golf is also the third most popular car this year after a Ford Fiesta and a Ford Focus.
Another Germany company, E.ON, formerly Powergen, will be keen to keep hold of its British business – worth £9.22bn in revenue.
E.ON is Europe’s largest electric utility company and the world’s largest investor-owned power and gas company.
With 39 power stations, including coal, gas, oil and wind, across the UK, the company has made massive investments in the UK energy industry which it will not want to lose because of pesky EU bosses.
French commercial insurance company Allianz is well established in the UK, employing more than 4,600 people in 26 offices.
Despite doom-mongering Remainers predicting a financial crash after last June’s EU Referendum, Allianz Group increased its operating profit from £36m to £96m.
The company is the 12th largest in the whole of Europe and with an overall revue of £100,137, its UK arm contributes a major boost to the company – and France’s economy.