Governments around the world are uncovering secret operations to expand China's influence - the work of a little-known branch of the Chinese Communist Party called the United Front Work Department. President Xi has called it his 'magic weapon'. Australia has changed its laws to combat foreign interference, and America says eight out of ten industrial espionage cases now involve China. So what is the United Front doing in the UK? Jane Corbin investigates this powerful but shadowy organisation. Has influence become interference as China bids to become the most powerful nation on earth?