'We had fond memories of our brother but the police have made them dirty'

Michael Hartley died at 18, leaving his family devastated and driving his mother into an early grave. Then an undercover police officer stole his identity

On Sunday 27 April, Honor Robson received a hand-delivered letter from a public inquiry. It was examining how undercover police officers infiltrated political groups over more than four decades. The letter revealed that her dead brother's identity had been stolen by a police officer who had penetrated two leftwing organisations. Using this false identity, the police spy had deceived a woman into a sexual relationship and had been prosecuted during his deployment.

Robson could not believe it. Her mind went back to another Sunday, 50 years previously, when police came to the family home to tell them that her 18-year-old brother, a trawlerman, was missing at sea, believed dead.