Viral video star was suffering from mental health problems

A London Tube commuter whose rendition of a Rihanna hit went viral in 2012 has revealed he was suffering from undiagnosed bipolar disorder at the time.

23-year-old youth worker Alika Agidi-Jeffs was filmed - without his knowledge - singing a Rihanna song with his earphones in, oblivious to his fellow commuters.

The video went viral when posted to Youtube garnering over 2.5 million hits.