Glojo, I don't think it does, and you do not know what the discount will be until you pay.
There is a list of discount amounts here that has been compiled
Halfords Trade Card - MoneySavingExpert.com Forums
And as said, remember as a Serviceman you can get this Discount card if you ermm qualify
Roadster, totally agree with what you say about the Hospitals, it was one of the perks of the job, a bit like having private medical care, and they allowed you some beers on the ward, subject to drugs etc