His widow Victoria, Commissioner Cressida Dick and Metropolitan Police Federation Chair Ken Marsh – on behalf of colleagues – laid floral tributes at a Memorial Stone that marks the spot where he was murdered.

A short Service of Remembrance was held.

The Rev Prevendary Jonathan Osborne told those in attendance: “We come here today to remember Jim Morrison. We give thanks for Jim’s passion for his work and dedication to duty and for his many gifts of character.

“We remember his warmth, his passion and compassion. For these and for all the memories we treasure and the love we have shared we give thanks.”

Jim, whose family were from the Hebrides but lived in Dumbarton where they were members of the Free Church in Latta Street,  was off-duty in the Covent Garden area on 13 December 1991 when he witnessed a handbag theft and gave chase. The suspect was cornered in Montreal Place where DC Morrison was fatally stabbed.

His killer has never been found.

DC Morrison’s widow Victoria said: “We had talked about the risk because of the job he did, but you never think it’s going to happen to you. It was devastating, life-changing for me and Jim’s family and all who knew him.

“It was a complete waste of a life, over a handbag, but being a police officer Jim always wanted to do the right thing and be law-abiding.

“At the end of the day people carry knives and are willing to use them at all costs. They simply don’t value life.

“I hope we can find the man who did this. Anyone who commits a crime like this would have to tell somebody, so there are people who know what happened and I would like them to come forward and tell it. Even after all this time it would mean everything to me and Jim’s family.”

There is a £30,000 reward for information that leads to an arrest and prosecution.

Over the years officers have followed leads in Germany, Belgium, Canada, France and Ireland in attempting to solve this case but with no breakthrough.

DCI Rebecca Reeves added: “Every year that goes by we make progress, but we are still short of the evidence that will signal a breakthrough in this case. I believe there are people who still hold vital information about who is responsible for DC Morrison’s murder.

“I want to hear from anyone with information about the suspect or about the group he was part of. The answers Jim’s family need could lie with someone who lived in London in 1991, but is now abroad. They may not know that we are still investigating, but we never give up. Thirty years on we are still investigating and will not give up the search for justice.

“If you witnessed or heard anything that could help us identify the man responsible for Jim’s murder, wherever you are in the world, come forward and speak to us. It’s not too late.’’

Anyone with information is asked to call the Metropolitan Police incident room on 020 8785 8267. You can also provide information via the internet by following this link: https://mipp.police.uk/operation/0101020107V95-PO1

Information can also be provided to independent charity Crimestoppers, anonymously, on 0800 555 111.