Looks like the pork pies might have been brought up by Boris to pre-empt their squealing they were losing the protectionism they had with the EU:
Mowbray’s pork pies are an institution in the UK. Fast food. They are about ok but look better than they taste. Worth trying.
Boris bringing it up is like an American president talking about Amerivan apple pie. The reference is to bring up home and comfort connotations