It was reported in 2018 that 40 convictions relating to drug driving had been quashed as the result of data tampering at a laboratory belonging to Randox Testing Services. Another 10,500 cases were potentially affected. Link

It seems that the company itself had acted as whistleblower, and two of its employees were arrested on suspicion of perverting the course of justice. Link

I have been unable to find any reports concerning prosecutions of the persons in question.