Campaigning organisation Open Britain claims that agriculture could suffer if existing trade agreements with the US are lost as the result of a hard Brexit: How trade could be derailed
19 trade agreements could be lost. Exports including beef, lamb and oilseeds could face new trade barriers. It is argued that these agreements will be lost once Britain leaves the EU unless the UK can negotiate new deals with the US, or negotiate to remain within the EU-US agreements, which in my view is not very likely. As far as a trade agreement with the US, the Americans are likely to want concessions on agriculture.
The agreements include food safety and animal welfare standards covering beef and pork as well as concessions on cereals and oilseeds.