Popular in Victorian times, they are sustainable, a good source of protein and brilliant for biodiversity, say those championing the bivalves

A splash of white wine, a handful of basil leaves and a few minutes preparation are all it takes to transform mussels that 24 hours ago were filtering seawater off the south Devon coast, into a delicious starter.

At the training kitchen in London’s oldest fish market, Billingsgate, in Poplar, we learn that fresh mussels require two vital preparation steps that the vacuum-packed, cooked variety don’t: “debearding” or pulling off the “byssus” thread that attaches the shell to rocks and other substrate, and the discarding of any with broken or open shells