US Ambassador: Post-Brexit trade deal 'difficult' with customs union

The US Ambassador to the UK says negotiating a trade deal post-Brexit would be "much more difficult" if the UK is in a customs union with the EU.

Woody Johnson also said it would be "more challenging" for the UK "to get control of [its] own trade policy".

But he said President Donald Trump is still hopeful that a "robust, big, very generous trade deal" can be done.