We'll just assume the publicists did not immediately return calls.

What can turn a son of privilege into such a hooligan?

You might be unfamiliar with Heathcote Williams. He's a poet and an activist. Doesn't like cars, which may explain the bonnet jumping. As his wikipedia entry notes:

But don't think he's some sort of humorless scold! Always a larf when Heathcote's about:

As for rejecting his kid, it's not clear whether Mr. Gilmour was responding to a recent rebuff, or his biological father's original act of selfish jerktitude:

Others might note that there is no more sombre enemy of good art than Mr. Heathcote Williams, but that's a matter of opinion.