The Walls website doesn't list a First Choice Pork Sausage but their top 'plain sausage', Succulent Pork, has the following ingredients:
Ingredients
74% Total Pork Cuts Pork shoulder (32%), Pork Belly (31%), Water, Pork Fat (11%), Rusk (Wheat), Potato Starch, Ingredients less than 2%: Salt, Dextrose, Yeast Extract, Dehydrated Onion, Stabiliser: Diposphates, Spices, Preservative: Sodium, Metabisulphite, Sage, Antioxidant: Vitamin C (E300), Spice Extract, Herb Extracts. !Contains Wheat, Gluten, Sulphites
Also
Typical values per 100g uncooked sausage - nutrition information
ENERGY 1376 kj / 331 kcal
PROTEIN 11.9 g
CARBOHYDRATE 16.8 g
of which sugars 0.7 g
FAT 24 g
of which saturates 5 g
of which polyunsaturates 4.1 g
FIBRE 1.7 g
SODIUM 0.6 g
SALT EQUIVALENT 1.4 g
There are people better qualified here to 'backwardly' project this formulation. But you know that the meat/fat is 74%, Water must be more than 11%, Rusk less than 11%, Potato Starch more than 2% and salt 1.4%. The rusk, water, spices exc. salt, chemicals and starch equal 24.6% if my calcs are OK.
You can view other sausage formulations here:
http://www.bangers.co.uk/products.cfmHope this helps
Phil