“…and The EU referendum were judged on immigration,”
Not by me (or anybody I know) it wasn’t. And criticism of the UK government (of any colour) is misplaced because immigration cannot be controlled whilst we remain an EU member.
“That prompted the forensic investigator to support his fellow officer by (probably illegally) publishing a page from his notebook.”
There’s no “probably” about it.
“I don't have any problem with Police Officers, serving or retired producing evidence.”
Is that so? Let’s imagine this then, Mikey. Your house is subject to a search under a warrant for, let’s say, stolen goods. No such goods are discovered. But in the course of the search the police find a shoe box full of pornographic pictures in your wardrobe. One of the officers makes a note of this in his notebook. A few months later, having retired, he knocks at your door and suggests you might like to make a small contribution to the “Widows & Orphans” fund to ensure this information does not reach your family’s ears. No problem with that?
“…but as he is not serving he is guilty of a past code of conduct breach. A slap on the wrist is all that will comeback to him.”
He should be investigated for “misconduct in a public office” (with which he can be charged even though he has left that public office because the actions he undertook – either photocopying or retaining his notebook without good reason – took place whilst he was still serving). The offence is indictable only (i.e. it can only be dealt with in the Crown court) and carries a maximum sentence of Life imprisonment.
As I said, I have no particularly high expectations of any Member of Parliament. They are all “here today, gone tomorrow” and for some tomorrow comes more quickly than for others. But I do have expectations that police officers and their assistants will behave properly when dealing with information they have gleaned through their privileged position.