Scott Morrison and Joe Hockey in Washington DC (Image: AAP/Mick Tsikas)

Drama is swirling around the Donald Trump/Scott Morrison September phone call. But perhaps the key question is: what prompted Australia’s US Ambassador Joe Hockey to write to American Justice Department chief William Barr about the issue, in swift and enthusiastic terms, a full four months earlier?

Hockey’s May letter to Barr, offering to assist in the investigation into the FBI's Russia probe, was sent without any formal request from the Americans and reflects our ambassador’s “how high?” reaction whenever the Trump administration asks him to jump.

Based on the letter, Trump and Barr might have expected an early response from Hockey and Canberra, but it appears not to have moved very quickly -- if at all.

Perhaps Trump groused to Hockey during one of their golf days, but by September, with nothing to show for the ambassador’s promise of “standing ready” to use our “best endeavours”, the president returned to the matter.