Out of interest, I had a look at the ingredients list of a packet of Walkers Roast Chicken and Smoky Bacon flavour crisps.
"Roast Chicken Seasoning contains: Glucose, Salt, Dried Yeast, Dried Garlic, Dried Onion, Potassium Chloride, Parsley, Flavouring, Colour (Paprika Extract), Dried Chicken Breast."
"Smoky Bacon Seasoning contains: Dried Milk Lactose, Salt, Sugar, Flavouring, Hydrolysed Soya Protein, Acids (Citric Acid, Malic Acid), Smoke Flavouring, Colours (Paprika Extract, Sulphite Ammonia Caramel), Dried Pork Shoulder."
So the flavouring does contain some actual meat, but as the very last ingredient. I don't know the precise details of the rules around use of terms like 'chicken' or 'bacon', which are not AIUI protected in the same way as 'Stilton', for example, but Walkers seem to think it's important to have a token meat presence in their meat-flavour products.
Once upon a time, I did a piece for the student newspaper comparing prices of a typical student shopping basket at the various local supermarkets. One of them, a big cash and carry type place, was selling tomato soup for 7p a tin. It didn't include tomatoes on the list of ingredients.