It was one of Britain’s brightest tech start-ups, praised by David Cameron, and a rare British “unicorn” – a company valued at over $1bn (£694m) before floating on a stock market.

Its dynamic founder Dan Wagner claimed last year that his business was worth $2.7bn (£1.9bn) and had signed a deal in China with “limitless” potential.

But last month Powa Technologies …

Read the full article at: http://www.bbc.com/news/technology-35860814