Britain will be left a “mangy old lion” as a result of Brexit, isolated from its allies and reduced to begging for trade deals from one-time colonies, a former Foreign Office minister is warning. Lord Malloch-Brown, who chairs the Best for Britain campaign for a second referendum, said that the UK’s loss of influence was exposed at last week’s G7 summit, where Theresa May was left a “spectator” to a clash between the US, Canada and the EU.