Liz Truss’s political interventions “should be like sex in a long and happy relationship, infrequent but anticipated with glee”, the former Conservative party chairman has said. Sir Jake Berry, formerly a key defender of Truss’s failed radical economic plans, said it was time for the former prime minister to figure out her new backbench role. Early on Friday, Truss made her second public intervention since being ousted from No 10, urging democratic nations to stand up to China and learn the lessons of not taking earlier and tougher action against Russia. Speaking in Japan in her first public speech since her resignation as prime minister, Truss called on the international community to agree on a coordinated package of defence, economic and political measures to support Taiwan. However, Berry suggested Truss should calculate how often she decides to speak out. “I think I’m suggesting that interventions by prime ministers should be like sex in a long and happy relationship – infrequent but always anticipated with glee,” he told TalkTV. Earlier this month, Downing Street said Rishi Sunak would always listen to advice from former prime ministers, after Truss used her first public intervention since stepping down to defend her failed attempt to boost growth. Addressing a conference in Tokyo, organised by the Inter-Parliamentary Alliance on China (Ipac), Truss said that in hindsight heralding a “golden era” of UK-China relations and rolling out the red carpet “sent the wrong message”. “Our response to the Russian invasion of Ukraine has been good and effective since the war started. But I regret that we in the west weren’t tougher earlier in response to aggressive and hostile actions from Moscow. “So when it comes to China, a failure to act now could cost us dearly in the long run. Our governments must signal to the PRC (People’s Republic of China) that military aggression towards Taiwan would be a strategic mistake. “The international community should agree a package of coordinated defence, economic and political measures to support Taiwan now.” Her keynote speech is being seen as an attempt to rebuild her political reputation, but also to add to pressure on her successor, Rishi Sunak, to take a stronger stance against Beijing. More hawkish Conservative MPs have called on Sunak to reclassify China as a “threat” instead of a “systemic competitor” in an update to the government’s defence and foreign policy strategy, which is expected to be published next month.