An undercover police officer stole the identity of a dead child to use as cover while working for a covert intelligence unit, it has been revealed.
The Undercover Policing Inquiry confirmed on Thursday that a Metropolitan Police officer, known as N596, used the cover name Rod Richardson while working for the National Public Order Intelligence Unit (NPOIU).
The country's largest police force said it would now offer a personal apology to the dead boy's mother, Barbara Shaw, who first made a complaint in 2013.
Jules Carey, Mrs Shaw's solicitor, said: "The gathering and use of dead children's identities by police officers for cover names was macabre and a gross intrusion into the private lives of families.
"The Metropolitan Police used Rod Richardson, Mrs Barbara Shaw's deceased son, as a cover identity between 2000 and 2003.
"The appropriation of her dead child's identity has caused her hurt and offence but so too has the fact that it has taken almost four years for the police to admit to her that her son's identity was used.
"The complaint she lodged with the Metropolitan Police in 2013 remains outstanding."
Some 42 cases have been found where dead children's names were used to provide cover identities for officers by the inquiry, launched last year to probe undercover police operations conducted by English and Welsh police forces in England and Wales since 1968.
A Metropolitan Police spokesman said: "We acknowledge this tactic has caused Mrs Shaw, whose deceased son Rod Richardson's identity was used, huge hurt and offence.
"The MPS will make every effort to meet with Ms Shaw, if she wishes, to apologise to her in person and explain how this came to be."
The inquiry was announced by then home secretary Theresa May in March 2015 under the leadership of Sir Christopher Pitchford, following revelations about the activities of undercover officer Mark Kennedy, who admitted having "intimate relationships with a number of people while undercover".
The controversial practice of assuming the identity of deceased children was used by Scotland Yard's secretive Special Demonstration Squad, the NPOIU and potentially other forces across England and Wales.
A spokesman for the inquiry said: "The officer known as 'Rod Richardson' was employed by the Metropolitan Police Service and worked for the National Public Order Intelligence Unit.
"The officer is not currently a core participant in the inquiry and will be making an application for a restriction order over his real identity."