Welsh Lamb is the official marketing brand of Meat Promotion Wales, for which The Agency is running a summer campaign.
The firm tracked down the former RAF Valley chef Gareth Matheson, who claimed that the burger was the prince’s "absolute favourite" while working at the Anglesey RAF base from 2010 to 2013. The story and the recipe were then provided to the media, with coverage from 21 July onwards appearing in UK and international media including The Telegraph, Metro, Mail Online, The Times and Loose Women.
This coverage created 170 million opportunities for individuals to see the coverage, and the number continues to rise, the agency said.
The agency also said it succeeded in reaching two million accounts through social media channels.
Social and PR director at The Agency, Lucy Aston, said: "There’s been so much interest in the recipe from around the world and across social media; the campaign has really put Welsh Lamb in the spotlight."
In other burger-related news, hamburger chain Byron announced its search for a retained consumer PR agency to support its regional expansion plan, PRWeek revealed last week.
This story was corrected on 31 July. An editing error meant it had said 170m individuals had seen the campaign.