The rise and fall of PC Mark Kennedy AKA Mark Stone - Mirror.co.uk

TO his fellow activists, Mark Stone – with his long hair, tattoos and piercings – was "one of them". He fitted right in.

But his appearance hid PC Mark Kennedy's real identity. He served in the Met until his covert operation began in 2003 when he was 33. He was eager to help with fines, a generosity that earned him the nickname Flash. He also travelled to 22 countries with his fake passport, gathering information about the international environmental scene.

However, a passport revealing his real name was found last October. Further digging revealed that he was a policeman. Confronted, Kennedy owned up. He has since left the police and lives abroad.

He told one activist his infiltration had been wrong, adding: "I'll just say I'm sorry, for everything. It really hurts."