Melt the butter, med low.
Once melted, add flour and work until a wet sand consistency.
Keep stirring, let it color until browned to close to the stock color or darker, about 15 minutes.
Start adding the stock, a little at a time, working it in well each time, until desired consistency.
Pepper well, season to taste with rosemary salt and marmite (a teaspoon at a time to taste).
Add the neck meat at the end.