Since his murder, I've not publicly commented on the passing of PC Keith Palmer for a lot of reasons – one being my own history with the Metropolitan Police. But today I want to make it clear: PC Palmer died a hero. He died as an exemplar of everything I advocate in a positive police force: officers doing their job properly, with honesty, fairness and integrity. PC Palmer died carrying out his service bravely. He made the ultimate sacrifice on behalf of us all.

As a former detective and officer of 11 years, working in the Manchester CID and London's Special Branch, I know more than most the dangers that are posed daily to officers. I was assaulted on duty several times; I was spat at, punched and kicked, while tackling those wielding knives.

Today the police will be out in full force, showing its might and strength to London and the wider world. It importantly will be a time for PC Palmer's family to say a public farewell after him dying in such horrid circumstances, before a private service.

It will also be a day for us to appreciate and give thanks to what policing should be all about – fighting crime and protecting people, as my former Chief Constable of Manchester often said. It's not an easy job, and appreciation has to be given for this.

Body of Westminster attack victim Pc Keith Palmer lies in palace chapel

Ever since I can remember, I dreamed of becoming a policeman so that I too could help others. For me that dream wasn't meant to be, but that doesn't mean I'm insensitive and cannot appreciate the men and women who are doing their jobs to the best of their ability without fear or favour.

There are those who think we shouldn't have such a public funeral for only one of the victims of the Westminster attacks, when several others died and many were injured. But PC Palmer was different. He died doing his job. It is right that he should be given full honours for the sacrifice he made, and I support a public call for any of the other victims too to have such a befitting funeral like his today.

London's policing is often criticised – and often rightly so. I have fought racial discrimination in the police through litigation, advocacy and public education. The police service is not perfect. It has its problems.

But that's why a day like today is even more worthy of our respect and acknowledgement. It is a symbolic moment that is important in terms of the preservation of our police service – celebrating the best of it, while not forgetting the worst, and confirming the essential role that the best police officers play in creating and upholding our tolerant, liberal society. Even as the Met faces up to its myriad issues, here is a country standing together to remember a man who stood for the best of the values of police; a man who fought injustice, though so many inside and outside the police force still perpetrate it.