Chief UK Brexit negotiator David Frost has called on Brussels to “shake off any remaining ill will” towards the United Kingdom for leaving the bloc as arrangements governing trade to Northern Ireland continue to prove contentious. The European Commission has said it will take legal action against Whitehall after the UK announced it was extending a series of “grace periods” designed to ease trade between Northern Ireland — which remains in the EU single market for goods — and Britain while permanent arrangements are decided. Mr...