In October 2015 President Xi Jinping was welcomed to Britain on a state visit, the event was seen as the pinnacle of the so called 'Golden Era' of warm relations between the UK and China. Over a decade later, and despite a cooling of that relationship, File on 4 Investigates discovers Chinese state money and influence reaching far into UK companies and universities as China targets British chip and blockchain technology, and asks whether enough is being done to mitigate the threat to national security.

Presenter: Paul Kenyon

Producer: Anna MeiselResearch: BBC Verify Junior Production Manager: Tom DunsterProduction Management Assistant: Tim Fernley Technical Producer: Cameron WardEditor: Tara McDermott