The Metropolitan Police/CPS response; brace yourselves

Sir
Thank you for sending me the disc. I have viewed it with a colleague and unfortunately there is not enough there to secure a conviction or give the male a PND for this offence of Sec 5 POA. I have spoken to a CPS lawyer who is based at Hounslow Police Station and on their advice their is not enough to secure a conviction and that the threshold test has not been met. I appreciate you will find this disappointing to hear and I can only apologise for that. For this reason the investigation will now be closed.
Kind Regards
[Police Constable]

My response:

Dear [Crown Prosecutor],

I refer to your decision that there is not sufficient evidence of a crime (specifically use of threatening, abusive or insulting words or behaviour within the hearing or sight of a person likely to be caused harassment, alarm or distress thereby, contrary to section 5 of the Public Order Act 1986) to give rise to a reasonable prospect of a conviction. I take it that you have decided this on the basis of the evidential test.
The evidential test should only be applied when all the available evidence has been reviewed and this includes an assessment of any Defence that might be put forward. If the allegation is put to the motorist and he admits making a threat to kill; then it seems to me incomprehensible that any potential prosecution would fail a merits test. If on the other hand he denies making a threat to kill (or exercises his right to silence), there is still my evidence that he made such a threat coupled with a repetition by me of what he said on a tape (which is equivalent to a contemporaneous note) and a further requirement to explain why he would have admitted threatening to kill me if he had not actually done so. At the very least the video evidence I have supplied you with provides strong corroborative evidence of my account which gives rise to at least a 50% prospect of conviction.
I have already informed the police that I retain the original and complete film recorded onto a mini SD card and I can think of no possible informed basis upon which anybody could doubt the admissibility of that evidence. Indeed a forensic analysis of the file may confirm my account of the actual words spoken by the motorist as he drew alongside me.
You are also bound to bear in mind that that threat from a car driver immediately alongside me is equivalent to making a threat with a loaded gun. All he need do to actually kill or maim me was to steer even further over to his left. This is an offence which should be taken seriously.
If it comes to a consideration of the public interest, you will no doubt bear in mind that cyclists are extremely vulnerable to harm inflicted intentionally or carelessly by motorists. There is a widespread perception that cyclists are often not enjoying the protection of the law to which they are entitled. Threats and abuse against cyclists is unfortunately widespread especially in the outer London boroughs and the main problem is (usually, though not in this case) securing sufficient evidence to take action against the minority of motorists who are determined to persecute cyclists.
I invite you to reconsider this decision and to refer it to a Senior Crown Prosecutor.

Yours faithfully,

Martin Porter

The evidential test is described in the Code for Crown Prosecutors (scroll down to section 4).