The 1K is supposed to refer to the platform type, ie 1K is a MK5 Golf, 5K is a MK6 Golf.
the VIN Is decoded like this
WVW - Manufacturer. Volkswagen
ZZZ - Filler letters, mean nothing
1K - Platform
Z - Another filler,
A - Manufacturing Year, A = 2010
W - Manufacturing Location, in my case Wolfsburg
****** - Serial Number of car
It seems the platform number is wrong, however on the boot label or the one in the service book it does say 5K underneath the VIN number