Harry,
There are others of course who will tell you that they manufacture name badges and crests, mugs ets etc, however, if you were to ask them if you could visit their factory premises (as I have requested in the past) you will probably find that they are purely 'middle men'
I know Terry and his wife Ann personally (Terry was on my sqn many years ago) I have always found them to be more than helpful and cooperative, and would recommend them to anyone.
Why don't you give them a ring on 01522 697000 and ask to visit their factory, I am sure they will make you welcome, and you will be able to see for yourself their setup.
I don't know if they have the monopoly on military sales, but if they do, then good luck to them! Check out the web site also and you'll see why so many sqns use them :
www.terrane.co.uk
The Winco