I just rang the old boy and he said there are two separate parts.
The first that pushes over the end he bought from Autobarn. It is called 'door edge protector'. It is chrome on one side and black on the other and does the job nicely (obviously black side out). The second part he explains looks like tonneau cover material with like a whipper snipper cord sewn in that gets squashed in between the two guards. Dad reckons he will make them up for his bikes.