Writing in the Mail, Mr Lucas said: “As Britain’s global, political and economic influence dwindles, China, patient and wily, is filling the gap — and the cooperative body that unites most of our former empire is ripe for picking. That would have seemed unthinkable only a few years ago.
He added: “Despite its name, the Foreign, Commonwealth and Development Office has consistently neglected our former empire.
“Dozens of embassies and missions in Africa, the Pacific and the Caribbean have closed as UK governments concentrated on promoting trade and investment in more promising climes.”
The Windrush scandal also “shrivelled British prestige” in Caribbean countries.
Mr Lucas claimed: “Chinese propaganda gleefully highlights these woes and fans resentments.