This was a really tough test for me, as a wholefood chef who cares deeply about quality. In this instance, animal welfare, provenance and processing were my main concerns, and there’s disappointingly little transparency on display. Some products claim to use British pork, a term that in itself has little, if any, meaning, not least in terms of traceability, sustainability or welfare; others boast of higher welfare standards without any certification. This week’s best bargain and best overall are therefore merely acceptable, rather than exceptional.Most of the sandwiches feature reformed ham, which is bulked out with phosphates and water, but some higher-quality ones are made with real ham – that is, sliced meat without added water; some of the best are made with shredded ham hock. Every single product contains additives, however. As for flavour, most are good enough only to fill a hole, but a few are genuinely tasty: moist, flavourful and fresh. And please butter your bread, supermarkets! Mayonnaise is not a substitute.The best supermarket ham and cheese sandwichesBest overall:M&S honey-roast ham & cheddar cheese£3.25 at Ocado★★★☆☆Light brown oatmeal and malted barley bread neatly filled with a double layer of ham and cheddar, with one side spread with soft cheese and the other with mayo. The only product in the test with clear welfare standards and the fewest additives (three). Contains palm oil.Best bargain: