SIR – Consider the following scenario: a demonstrator walks up to a policeman and pushes him to the ground.

The policeman seems to recover, but then collapses and dies. The whole thing is captured on CCTV and by mobile phone cameras held by witnesses. The post mortem shows that cause of death was from internal bleeding.

How long would it have been before the police charged the demonstrator with unlawful killing? I suggest that it would have been very few days before this happened.

Consider the opposite scenario: a policeman pushes a man who was not involved with the demonstration.

He falls and dies as described previously. Members of the public publish what happened and a national newspaper gets hold of CCTV footage that backs up their film.

There is then a period of 17 months before the DPP decide that there is conflicting evidence and not enough chance of a conviction; in fact, so much time has elapsed that a charge of common assault cannot even be brought.

I call upon the director of the DPP, Keir Starmer, to resign: having hung his head in shame.

I also call for a public fund to be set up so that the family of Ian Tomlinson can afford to bring a private prosecution.

Ian Parsons, Alexandra Road, Eccleshill, Bradford