Sorry to hear about the theft BG and it's a pity the medals weren't named.
I had my medals stolen from the car after a dinner a Wattisham a few years ago. Suit and medals locked in boot while walking in Rendlesham Forest the day after, came back to find car broken into and boot crowbarred. We drove to the local police station to report the theft (passing a 'campsite' just down the road) and did the necessary paperwork.
A good few months later, a package was delivered to my home with the medals. A medal collector had spotted them and they were handed over to the police. I don't know how the collector knew they were stolen and as I didnt have any details I've not been able to thank him/her personally, it was great to have them back.
Perhaps something in a local paper will see your Grandfathers medals 'reappear'.