Most of the sewage spills into England's waterways in the last two years may have been illegal but gone unpunished, according to new analysis.

UK law states that raw sewage should not be released during "normal" weather conditions, yet until now the regulator has not clarified exactly what that means.

But campaigner Prof Peter Hammond obtained a definition in secret court papers, and said it shows that for more than 80% of the time sewage was being spilled, the weather was "normal" - making the spills possibly illegal.