Police have dropped a “terrifying” investigation of a former academic researcher for a tweet she posted that was critical of a transgender GP.

Maya Forstater, now the executive director of Sex Matters, which campaigns for clarity about sex in law and policy, was told on Thursday evening that police would take no further action against her.

This came after she was investigated for 15 months by Scotland Yard.

The Metropolitan Police appeared to have “sat” for two months on the decision that no crime had occurred before informing her on Thursday evening, just a day after The Telegraph published a story about her plight.

Forstater had told the newspaper that her experience had been “Kafkaesque” in that she had not been told anything about what tweet she was being investigated for or who had made the complaint until she agreed to turn up to a voluntary interview with officers or face arrest.

“The whole process was Kafkaesque. It has been very stressful and intimidating. It has felt like I have been questioned by a political body, not by the police supposed to be treating people without fear or favour. So it was terrifying.”