The Determining Identity and Nationality in Local Policing report also revealed that 435 foreign nationals were arrested in the same area and period – accounting for 25 per cent of all arrests.

‘The research demonstrated that more rigorous practices in custody suites could increase the number of foreign nationals and illegal migrants who are identified as being involved in criminal activity,” its authors said.

‘In some sites there was a marked reluctance to challenge arrestees who claimed to be British, even though officers suspected that the claims might be false.

‘This reluctance was commonly ascribed to the fear that any such challenge could result in an accusation of racism.’