In glorious slow motion, mouth-watering food is depicted while the sound-track delivers a sensual narrative underlining the food's impeccable and exclusive origins, beginning: "This is not just ... this is ..."
The adverts are so popular they have even sparked a large number of copycat campaigns.
But the next luxury food to have its wholesome origins emphasised by the high street retailer is its "Lochmuir salmon" - despite the fact that "Lochmuir" doesn't exist.
The store admits it has created the fictional location to brand its new quality salmon.
Though it sounds Scottish, the name Lochmuir was invented by marketing experts at M&S. The chain's successful Oakham chicken - featured in the TV ads - is also named after a fictitious location.
It raises the issue of food provenance at a time when shoppers are more wary than ever about where their groceries come from. Consumer wariness at misleading labels led to the European Union introducing a list of "places of designated origin" for products such as Stilton cheese and Parma ham.
But not everyone has been pleased with the M&S way of branding. An MP demanded the firm change its Oakham chicken because it shared its name with a market town in his East Midlands constituency while the birds were actually bred in Norfolk and Suffolk.
Of Lochmuir, Andrew Mallinson, M&S fish expert, said: "It's a name chosen by a panel of consumers because it had the most Scottish resonance. It emphasises that the fish is Scottish."
The Scotsman understands Lochmuir salmon is in fact being farmed at five sites north of the Border by supplier Scottish Sea Farms after three years of research. It is grown more slowly than other fish and has a special feed to make it rich in Omega-3.
Edward Garner, communications director of analysts TNS-Worldpanel, said: "This idea fits in with the strategy of high-end retailers such as M&S and Waitrose whose advertising emphasises the effort that goes into sourcing the best produce."
He added that sales of fresh salmon were up 9.4 per cent year on year, worth 388 million annually, as consumers moved towards healthier foods such as fish. Frozen salmon sales were also up 8.3 per cent. "Salmon has become commoditised, and this move by M&S is a good way of making a product stand out from others on the shelf."
Dominic Morrey, trading director for M&S, said: "We have taken the same principles of Oakham chicken and applied them to fish and believe we have a real leading-standard offer."