Liam Allan with his mother, Lorraine Allan, and supporters at Croydon crown court. “I knew the truth,” she said yesterday after her son was cleared of all charges

A judge has called for an inquiry after the trial of a student accused of rape collapsed because police had failed to reveal evidence proving his innocence.

Liam Allan, 22, spent almost two years on bail and three days in the dock at Croydon crown court before his trial was halted yesterday.

The judge demanded a review of disclosure of evidence by the Metropolitan Police, Britain’s biggest force, and called for an inquiry at the “very highest level” of the Crown Prosecution Service (CPS). He warned of the risks of “serious miscarriages of justice” after hearing that, to save costs, material was not always handed to defence lawyers.

Mr Allan, a criminology undergraduate at Greenwich University, had been warned that he would be jailed for