Surreytraveller, yes police warrant cards are governed by law and remain the property of the police force you are/were serving. When I finished at the end of last year, I had to hand my warrant card in and it was signed for by one of the central HR staff (who then destroy it for security reasons).
The federation who are the police union regularly arrange various offers to it's members which includes discounts for certain high street shop purchases, restaurants, gym membership and family attractions but this all comes to an end once you leave the service. However, a cop that completes thirty years and retires still gets certain privileges but not all of them.
During my fifteen years service I hardly ever took advantage of the offers as it meant producing my warrant card when paying for anything and I was totally commmited to not abusing my position whether on duty or off. I saw many idiots in the service abuse privilages with their warrant cards and this invariably ruined some great deals. A prime example was the free or discount brews at McDonald's that were stopped as a result of the halfwits from the Firearms Unit helping themselves to half the menu and refusing to pay!!!
C J