Midmum / Migky, my understanding is that it only applies to CWGC graves, and not family headstones or memorials, I recently identified a headstone of a South Lancs man from Wigan who was murdered as a POW, his name was Culshaw, and his headstone had said Gulshaw for the last 65 years.
The CWGC are currently in the process of replacing the headstone.
ps, Midmum, Pm sent with contact details.
Migky, still in the process of writing something up for the Manchesters website.
Phil