Princess Diana's Brother - Much like ? Goldsmith Story

I was told on a few occasions (gossip) that Diana was actually not Plantagenet (as my family are) but the daughter of Lord Goldsmith, a very nice man by all accounts - her mother had apparently reason to wander. Is it false or is it true . Franky, Zac has been in Richmond long enough to have sorted things out before now, I don't trust him, especially since viewing high-rise flats overlooking Richmond Park, disgraceful disregard for the security of the identity of the UK