A senior economic adviser to Donald Trump has said it would take “an extraordinary deal” for any country, including the UK, to improve on the 10% tariff rate the US has imposed almost worldwide, pouring cold water on Downing Street’s hopes for a breakthrough. Trump succumbed to pressure from plunging financial markets on Wednesday and temporarily reduced “retaliatory” tariffs on all countries to 10% – barring Chinese goods, which face a rate of 145%. For the UK, this is no change from the levy imposed when Trump announced his “liberation day” agenda, but Keir Starmer’s government still hopes a free...