You’d be surprised at how few importers actually provide most of the imported foodstuffs in the U.K. - Lamex and IPL for instance. Brexit has made importing untenable for a lot of smaller operations due to the red tape, and many have moved their buying to import agencies or domestic wholesalers.

There are quite a few significant supply bottlenecks in the U.K. food supply chain, from supermarkets to wholesalers to importers, and they do allow for price fixing - demonstrably so in the case of supermarkets and domestic produce.