But while the substance of their testimony was damning for Trump, the first day of public hearings fell flat as a form of political theatre. This was not a hearing to electrify the nation. Neither was it one likely to change many minds. Top US diplomat in Ukraine William Taylor testifies before the House Intelligence Committee on Capitol Hill. Credit:AP Democrats have viewed Taylor, in particular, as their potential star witness and it was easy to see why. The Vietnam War veteran has served for decades under Democrats and Republicans; earlier this year the Trump administration made him the top US diplomat in Ukraine. It's impossible to paint him as a political hack, and the Republicans on the House Intelligence Committee didn't even attempt to do so.

Speaking calmly and methodically, Taylor explained how his experience representing the Trump administration in Ukraine became increasingly "confusing, and ultimately alarming". It was the diplomatic equivalent of Alice stepping through the looking glass. US President Donald Trump. Credit:Bloomberg Illustration: Matt Golding Credit: He described learning about "an irregular, informal channel of US policy-making with respect to Ukraine" led by the President's personal lawyer Rudy Giuliani. Rather than promoting official US policy, the members of this channel were focused on encouraging Ukraine to investigate Trump's potential 2020 rival Joe Biden and his son Hunter who had worked for a major Ukrainian energy company.

Taylor recalled how he and others "sat in astonishment" as they discovered that the US was withholding crucial military aid from Ukraine – a decision he said would cost Ukrainian lives. It was "crazy", he wrote in a text message to fellow diplomats, to make US security assistance contingent on a partisan investigation. Loading Taylor was mostly repeating evidence he had previously given during the private hearings – but he came armed with some new information. He revealed that an aide had overheard a July conversation between Trump and the US ambassador to the European Union Gordon Sondland in which Trump asked for details about the Biden investigation.

This second-hand account of an overheard phone call has been widely described as "bombshell" evidence. That's overkill. It's not news that Trump wanted Ukraine to investigate the Bidens. The transcript of his infamous conversation with Volodymyr Zelensky showed him asking the Ukrainian President to look into the issue. Trump later stood on the White House lawn and publicly called on Ukraine and China to investigate the Bidens. Loading Replay Replay video Play video Play video The problem with Taylor and Kent's testimony is that Trump remained a peripheral and largely mysterious figure throughout.