i was told by him today that he had finally received paperwork from them for another litter registered in APRIL.

Do some of these 'breeders' think the general public are so soft and daft. They must think the general public have brains the size of peas.
Two weeks is a looooooong time to wait for paperwork, today paperwork submitted takes days to process. Even if lost in the post *rolleyes* it takes nothing to send another lot out.
These 'breeders' infuriate me, that they treat their puppy buyers like such idiots.
Ring the KC and as suggested ask if the litter is being processed, if not you have your answer, if you were brave enough I'd take back the pup but people like this rely on the fact that you won't.
Always take your pup with paperwork, if it is not there walk away. Unless the breeder has exceptional circumstances for not having the paperwork ready, they have 8 weeks to send it off, there really aren't that many excuses not to.