"Which is nonsense, UK trade with the EU is increasing, and in 2017 was the highest it has ever been:"

In this present discussion trade is a two way street and is a somewhat perfidious term, if attempting to make a point. The crux of the matter is the balance of payments and their short term and long term trends. Defining increasing decreasing trade defines nowt. The figures for imports and exports need to be considered and whether they positive or negative and for how long.
"The share of UK exports going to the EU has declined gradually over recent years. In 2006, the EU accounted for 55% of UK exports. By 2017, this had fallen to 45%. The picture on imports is slightly less clear. In 2002, 58% of UK imports were from the EU. By 2010, this had fallen to 51% but has increased slightly more recently, reaching 54% in 2016. Over time both imports and exports to the UKfrom the EU have dropped.Also these figures pay no account for the rotterdam effect of being an entrepot port for certain British exports.(BRIEFING PAPER
Number 7851, 4 July 2018 House of Commons)