My understanding is that it's not unprecedented at all... my example of George V issuing a LP to restyle Pss Patricia of Connaught on her marriage, minus her HRH and no longer a Pss of UKoGB&NI . Also the LP issued in 1937 to deny the wife of the Duke of Windsor ( an HRH ) to the entitlement of HRH. TK can certainly issuue a LP to remove the HRH and title of Prince for his brother based on these two previous LP. Of couse it's a murky old business doing such a thing ...so my guess is he won't..he ( his advisors) will let the UK parliament sort it out ...and there is no room for that right now. The govt has enough to deal with rather than sorting out titles and removal of for TK's brother.