This reply arrived today:
Thank you for your email and apologies for not coming back to you sooner, I have been out of the office.
I hope the following explanation helps! The sausage is make with 80% pork in the raw recipe, but the ingredient declaration reflects the product once it has been cooked. The 1st cook which we do before we send into the Coop gives us 10% cook loss and the 2nd cook in store removes a further 15% of moisture, therefore the mathematical calculation is 104g of pork per 100g of finished product simply due to the moisture loss in the product through cooking which then concentrates the pork value.
This does comply with labelling guidelines however you are right its very confusing and we are investigating how we can declare this in a better way and make it more user friendly.
National Account Manager
Holmesterne Foods Limited
Nope ... I'm none the wiser ....