Earlier this month, I attended a delightful dinner in New York with a collection of Republican luminaries. Unsurprisingly, the conversation was dominated by the topic of Donald Trump — and many of those assembled were deeply anxious.

Little wonder: in recent days Mr Trump, the presumptive Republican nominee for president, has delivered another stream of invective that makes many top party members cringe;, or, more accurately, long for the patrician self-control of a man such as George HW Bush.

But tThis particular dinner included an intriguing twist: the main speaker at the table was a charming Republican power broker who I shall call “Bob”. And Bob had arrived with a mission to “sell” Mr Trump — verbal gaffes and all. Bob has dealt extensively with The Donald for many years and endorsed him. And now he has embarked on the challenging task of persuading other elite Republicans to do the same.