The lambs are reared on National Trust land and produce the only meat in the UK to bear the National Trust logo, after the estate won the Trust's first-ever gold medal for produce.
Sainsbury's is planning to capitalise on the win by putting the medal logo on packaging and PoS material. It already sells at a premium compared to other Welsh lamb under the Taste the Difference range.
Sainsbury's lamb buyer Stuart Wright said: "It's a really good example of how we've worked with farmers to provide a special product. It goes into 25 stores in Wales, the Borders and in çentral London."
Distribution is limited because the eight farmers on the estate together produce only 250 lambs a week, Loin chops sell for £12.59/kg, compared to £10.99 for standard British lamb chops.