UPDATE:
Having taken a closer look in daylight the “split” is actually a deep score, it must have been a nail or screw sticking out of the post. I underestimated the length it is 44cm or 17 5/16” old school.
The car is a 13 month old Kuga and I was going to take it down to the Ford garage and see what they said. However, when we bought it we took out an additional cosmetic repair insurance which should now cover the cost of repair. I had similar damage to an earlier model and it was repaired and you could not tell the difference, so will get onto them on Monday.