Britain has lost its top 'AAA' credit rating after being downgraded to 'AA' by rating agency Standard & Poor's (S&P) following the UK's decision to leave the European Union. Meanwhile, Fitch Ratings also lowered its rating to 'AA' from 'AA+', forecasting an “abrupt slowdown” in short-term growth. This follows Moody’s downgrade on Friday, the day the referendum results were announced.