M&S MACARONI CHEESE:

A typical ready-meal with a plastic tray and film top. The film can’t be recycled but in theory the tray can. But it emerged this year that because the trays are black, the sorting machines are unable to detect them. As a result, up to 1.3 billion trays may be dumped or burned each year. Steps are underway to introduce a new pigment to coat the trays.