All eyes were supposed to on Capitol Hill yesterday as Donald Trump finally secured support for his "historic" tax reform plan, which he believes will be the biggest achievement of his administration.

Instead, America's attention switched as an unexpected political bombshell exploded less than a mile away at the E.Barrett Prettyman District Courthouse.

There, Michael Flynn, Mr Trump's former national security adviser and close confidante, a man accustomed to chatting one-on-one with the president in the Oval Office, delivered a potentially Brutus-like wound to Mr Trump.

In the previous 24 hours Mr Flynn, always regarded by Mr Trump as a staunch loyalist, had decided to co-operate with Robert Mueller, the special counsel investigating links between the president's campaign and Russia.

Mr Mueller had placed intense pressure on Flynn, threatening to bring legal proceedings against his son, Michael Flynn Jr, unless he agreed to "flip" and tell everything he knew to the investigation.

Flynn, 58, looked grim-faced as he arrived at court. He was required to take off his jacket and waist belt, and to hand over his glasses case, as he went though security. The former Army general sighed as he did so.