Originally posted by the Voice of America. Voice of America content is produced by the Voice of America, a United States federal government-sponsored entity, and is in the public domain. 'Salmon for Stetsons': Britain Hopes US Trade Deal Will Pressure Europe Henry Ridgwell LONDON - Britain and the European Union began crucial talks this week on their future trading relationship after the Brexit transition period ends December 31, leaving less than 10 months for the two sides to negotiate and ratify any deal. On the same day as the talks began, Britain published its negotiating position for a trade agreement with the United States. London hopes the parallel discussions will give it leverage in negotiations with Europe. Prime Minister Boris Johnson promised to 'drive a hard bargain' with the United States as Britain published its mandate, pledging a boost for both economies as Britain traded "salmon for Stetson hats." Beyond the stereotypes, Britain wants to open up markets in areas like car manufacturing, professional services such as law and architecture, artificial intelligence, big data and food processing. Formal negotiations are expected to begin later this month. The best-case scenario is a $19 billion boost for the British economy over the next 15 years or 0.16 per cent of GDP, according to government figures. "That's 0.1 or 0.2 percent you wouldn't otherwise have, so that's fine," says trade expert David Henig of the European Center for International Political Economy. "I think President Trump said it might double or triple U.S.-U.K. trade. That was unrealistic," he said. However, the government's forecast also suggests Brexit will cost the economy far more -- around $168 billion or 6.7 % of GDP growth, even with the type of trade deal envisaged by Boris Johnson. "For the UK, the EU is our largest market. It's approximately 50% of our trade and whilst deals with the U.S. or Australia can help a little bit, nothing will really replace that," said Henig. Britain has also ruled out opening up key areas of its economy to the United States. .