Guido can confirm that John Prescott’s son David is joining Jeremy Corbyn’s office as his new speechwriter. Prezza Jnr is best known for denying that he tweets the gags from his dad’s Twitter account, so maybe we’ll be seeing a new, joke-telling Jez from now on. David is not exactly a Corbynista, he worked on the Andy Burnham leadership campaign. He has long felt that the “Red Prince” tag held him back in finding a safe seat. Nonetheless a canny hire by the leader’s office…