I do understand. It's about the public procurement directive in public sector catering, including the House of Commons. We have to comply with that, so we aren't allowed a “buy British” policy. However, once we leave the EU, we would possibly be allowed a “buy British” policy, or indeed, if we get “Canada-plus” plans, a “buy Canada” policy.
On February 28th, 2019. See this statement in context.