I'm not completely sure but I don't think that the 16th like the 17th gives a distance, if i'm wrong then I will gladly like to be put right, but there is something in the back of my mind that says 300mm
In Scotland I believe the building regs make it 300mm for a sink, but again I'm not sure of that. I know though that the BRB don't give you a distance and therefore you have to work to the regulations covered in 522.
I think you have to do a risk assement here. If the socket is RCD protected then I may just not code it. but mention in a report that it should be moved under regs 522
If it is not RCD protected but the diconnection times are met then perhaps a code 4, again with a recommendation that it be moved under regs 522