How dangerous for the UK economy is the European Union’s latest advice to Continental firms?

Press quote (The Independent)
06 June 2018

Sam Lowe of the Centre for European Reform think tank says that sectors which traditionally find rules of origin burdensome include textiles, food, machinery and vehicles.For instance Mr Lowe of the CER reports that Korea is asking, in return, for Chinese inputs to its own cars to be treated by the UK as though they were Korean.
...Mr Lowe points out that the incentive for the European Union side to solve the Brexit rules of origin problem might be blunted due to the fact that if EU companies do start sourcing more in the rest of the EU that’s a potential spur to growth and jobs within the bloc.