"After British law enforcement spotted him and demanded to know what he was praying for, Adam replied simply, it was on behalf of the unborn son he and his former girlfriend had aborted years before," Mr Vance said.
Mr Vance's speech was the latest wake-up call for the UK and European nations in terms of security and the Trump administration's new foreign policy aims.
"When I look at Europe today, it's sometimes not so clear what happened to some of the Cold War's winners," he said, taking the leaders to task on issues like migration, security and democracy.
Mr Vance criticised the country for the jailing of 51-year-old Adam Smith-Connor - who was imprisoned for breaching a safe zone around an abortion clinic in Bournemouth.
JD Vance has taken aim at the UK and Europe over what he claimed was "backsliding" free speech and democracy.