Police Constable James Gordon, 26, was attacked with iron bars as he stopped a gang of men breaking into a boiler works factory in St Helens, Merseyside, in 1893.
Although his death is listed in official police records, his grave at St Helens Cemetery was left unmarked.
But 120 years later, Brenda Neary, a former Merseyside police officer and volunteer at the cemetery, tracked down his resting place.
The Police Roll of Honour Trust commissioned a specially engraved headstone to be erected on the grave at a dedication ceremony to mark the anniversary of the Scotsman’s death.
The headstone was unveiled by the chair of The Police Memorial Trust, Geraldine Winner, the widow of Michael Winner, who formed the organisation following the death of Pc Yvonne Fletcher who was shot outside the Libyan embassy in London in 1984.
Speaking at the graveside to those in attendance, Mrs Winner said: “Michael formed The Police Memorial Trust in 1984 and to date it has honoured the lives of 45 fallen officers.
“This service is the first to honour one since Michael passed away and the first ever to pass across the centuries.
“Michael would have been so proud to be here.
“I am so thrilled to be part of Michael’s legacy which allows me with great pleasure to dedicate this memorial.
“No officer is ever expected to lose his or her life on duty but where regretfully it happens the Police Memorial Trust and the Police Roll of Honour Trust exists to honour the fallen.
“Pc Gordon has not been forgotten.”
Mounted police officers from Merseyside Police led the official party in the cemetery as a guard of honour was also formed leading up to the grave.
Police cadets, police community support officers and members of the National Association of Retired Police Officers were also among up to 200 people who gathered to pay their respects.
The memorial service was led by the Rev Keith Hitchman, force chaplain of Merseyside Police, along with the Rev Gary McGowan, of St Helens United Reformed Church.
Sid Mackay, chairman of the Police Roll of Honour Trust, did a reading from the Bible.
The Last Post was played by a bugler before a minute’s silence was held in remembrance of Pc Gordon and for all fallen police officers.
Floral tributes were laid at the headstone as the Piper, Detective Sergeant Jim Gray, wearing traditional Highland uniform, played a lament.
Pc Gordon’s sacrifice is remembered at The National Police Memorial in The Mall, London, which was opened by The Queen in 2005 but it remains a mystery as to why his grave was unmarked.
Born James Reid Gordon in Fordoun, Kincardineshire, Scotland, on January 19, 1867, he was the son of Robert and Jane Gordon.
The Rev McGowan told those at the remembrance ceremony that the family were of “good farming stock” with the head of the household being described in the National Census as a ploughman and the rest of the family as farm servants.
His father died in 1880 which left his mother to fend for James and his seven siblings, one as young as five months old.
In 1889 he moved to St Helens where he lived in Union Street and on July 4 of that year he joined the St Helens Borough Police force and became Police Constable 57.
He also became a member of the local Presbyterian church in Calder Street where his communion roll showed the names of four other police officers who had also originated from Scotland.
After his training he was stationed at the police office in St Helens Town Hall.
During that period it was a challenging period for keeping law and order at a time of the first miners’ strike and a national strike over wages.
Just four-and-half years into his service he was the victim of an unprovoked attack on November 12, 1893, when he and a colleague disturbed three men who had broken into Foster’s Navigation Boiler Works in Atlas Street.
He was given first aid for his head injuries and then sent home but died a short time later in the early hours of November 13.
His three attackers, said to be colliery workers, were found guilty of murder following a trial at Liverpool and sentenced to death, although their sentences were later commuted by Queen Victoria to 15 years of hard labour.
On sentencing, Mr Justice Day said to the men: “The policeman’s life had been sacrificed whilst he was discharging his duty.
“The poor fellow was in the prime of his life, being just 26 years old and he treated you with every conceivable consideration. He had, however, been hurried into the presence of his Creator without a single moment’s warning owning to the brutal violence of you, the prisoners.”
The Rev McGowan said Pc Gordon was described by his fellow officers as “an affable, good-tempered young fellow, brave as a lion, and at all times to be relied on in the performance of his duty”.
Pc Gordon was buried on November 16, 1893 and at his funeral were mounted police officers from Liverpool, a large gathering of officers from Liverpool and St Helens, and local townsfolk. Also there were dozens of members of his Presbyterian bible class.
The police and public of St Helens donated about £30 which was sent to his widowed mother in Scotland.
Steve Lloyd, the Trust Manager of The Police Roll of Honour Trust, said: “As an organisation we have never had a murdered police officer in an unmarked grave before.
“This proves the job of a police officer never changes. It will always be inherently dangerous.
“We may never know why this local police hero was left in an unmarked grave. The Trust are pleased to be able to make his grave so that everyone will know where young Pc James Gordon lies at rest. His duty well done.”
Superintendent Chris Markey, of Merseyside Police, said: “Every day, police officers go about their duty and do not know what their day could bring. Pc Gordon’s death is a reminder to everyone that, on a daily basis, officers can be called upon to go into unexpected situations, and show great bravery and courage usually when other people are at the worst moments in their lives.
“Merseyside Police is pleased that his passing has been commemorated in this way and hope that this fitting memorial will serve as a constant reminder of his sacrifice for the community he served here in St Helens.”