It is coincidental that this subject has come up on Pprune as last weekend I was standing in the churchyard at Benningborough where the military graves from RAF Linton upon Ouse are buried.
There is an military plot with standard CWGC headstones but amidst those military rows are two civilian headstones of military personnel which are in a state of dilapidation. One is of a young Sergeant Pilot who was killed in 1939 and the other is of Group Captain Frank Garraway who was killed in a Luftwaffe air raid on Linton in 1941 and who after whom the "Garraway Room" in the Officers Mess is named.
I know that with defence cuts nowadays personnel are at a premium but I thought it might be respectful if the existing RAF personnel from Linton took a few hours off to clean up the two civilian graves.
The graves are still classed as war graves even if marked with private headstones and as I understand it, the CWGC will place a standard war grave headstone to mark the grave once the private one has deteriorated or if any family request it.
Found this in "Courage Remembered"
These privately (and frequently privately marked) war graves are inspected by the Commission's staff. If the marker is found to have deteriorated, the Commission offers to replace it with a standard Commission headstone, at it's own expense. Next of kin frequently offer to accept this offer, as not only is a new headstone supplied, but maintenance then becomes the Commission's responsibility for all time.