As I surmised, a better informed reader would respond to my cry for help for details of the legal minimum for meat content in our sausages rather quicker than the various official bodies in charge of this critical part of our gastronomic heritage. Below is Gerry Danby’s comment. It is succinct, a model of clarity and rather depressing.
The term ‘sausage’ is a reserved description which, in the case of pork means not less than 42% meat and in all other cases 32%.
Note that ‘“meat” means the skeletal muscles of mammalian and bird species recognised as fit for human consumption with naturally included or adherent tissue but does not include mechanically separated meat as defined in point 1.14 of Annex I to Regulation (EC) No 853/2004.’
Take a look at http://www.artisanfoodlaw.co.uk/traditional-foods/meat/meat-introduction and scroll down to section 3. The reference to the 2003 Regulations needs updating to the Products Containing Meat etc. (England) Regulations 2014 (http://www.legislation.gov.uk/uksi/2014/3001/contents/made) but similar provision is made in Schedule 1. The definition of ‘meat’ can be found in regulation 2.
It also turns out that our sausages and other meat products cannot contains MSM (Mechanically Separated Meat) thanks to an EU directive. Well, that’s a relief.