By James Davey LONDON (Reuters) – Unilateral action by Britain to overrule post-Brexit rules agreed with the European Union for trade in Northern Ireland could harm all UK consumers if there was retaliatory action by the EU, Britain’s retail industry warned on Wednesday. Andrew Opie, director of food and sustainability at trade body the British Retail Consortium (BRC), told lawmakers the government needed to remember that 80% of the UK’s food imports come from the EU. “Our concerns would actually be about the wider impact potentially to all consumers in the UK if there was any kind of retaliat…