Managed to resolve this. I was told that if I had the radio serial number (which is on the rear of the radio) then I would be able to obtain the code. From eBay I bought the special keys to remove rather radio, the keys cost me less than £2. When I removed the radio I was very lucky to find the the code had actually been written on a label attached to the top of gage radio. Problem solved, code recorded and radio now decoded and fully operational.