"Disabled parking signage"

I was visiting my wife in Arrowe Park hospital and on the way out was paying my parking ticket somebody behind me said hey mate, you don't have to pay as he could see I was disabled. I was taken aback as I always pay for parking there although I have a parking blue badge. I purposely went around the disabled bays to look for signage as to disabled free parking signs. And there is none at all it is almost as though they don't want the disabled to know. I wonder how many have paid needlessly in the past including me?