Thomas Markle gave a wide-ranging interview on "Good Morning Britain" and revealed Harry once tried talking him off the ledge over the Prez. Thomas said he had been in a bad mood about something Trump had just done when he got on the horn with Harry.

Thomas said, "I always have a bad attitude about Donald Trump and that's never gonna change. I have to apologize to the rest of the world for my president. All Harry actually said -- because Trump was new -- 'Give him a chance.' I think Harry's probably changed his mind by now. I certainly hope he has."

That's a stunning revelation given members of the Royal family are supposed to remain apolitical ... and especially interesting since Harry's boys with President Obama.

Thomas also said Brexit was loosely discussed ... Thomas says Harry told him he was "open to" the experiment of Britain leaving the European Union.

But lighter topics were also discussed ... Thomas dished on talking to Harry for the first time, and he also shared how Harry asked for his daughter's hand.