As a retired detective superintendent in CID, who spent the best part of 25 years investigating terrorist-related and other crimes, particularly in north and west Belfast, I spent a great proportion of my time working with informants.
I always had an abiding interest in crime-solving and when I was a first-year probationary uniform constable, I practically stumbled into the world of intelligence-gathering when I managed to, metaphorically, corner a well-known criminal into a compromising position and, much to my surprise, he began to offer information on others in return for a certain course of action by me.
I took up his offer and he gave me the names of the top UDA assassination squad, which was known locally as 'the Dirty Dozen'.
I confess to having gained a certain buzz out of this encounter and, not long afterwards, a detective whom I was friendly with asked me to target an active criminal who was habitually driving while disqualified - an offence which normally carried a sentence of four weeks' imprisonment.
While on mobile patrol a few days later, I spotted our man driving and, after a short chase, I nabbed him. He, too, began to horse-trade with me and offered up another prolific criminal, who was considered a walking crimewave and much sought by the local CID.
A simple operation was put in place and I made the capture and handed him over to the CID, to which he admitted 120 crimes.
I was now becoming hooked on this aspect of policing and, not long afterwards, I was accepted into CID. This gave me a greater opportunity to continue 'trading' information and I made the most of it.
Soon I became much more cynical in dealing with such people, many of whom initially refused any financial reward which, perhaps, helped ease their conscience, but I persisted until they began to accept small amounts of money. Finally, I made them dependent on the income and snared them completely.
Purists will readily call this a form of blackmail and to such people I readily defer, but, as the terrorist campaign intensified, it was infinitely preferable to going to the casualty ward (or the mortuary) if I could prevent such atrocities from happening.
The payment some of them received was, on occasions, small reward for the dangers of walking the tightrope between life and death if caught out by the likes of that consummate spycatcher 'Stakeknife' (Freddie Scappaticci).
As I moved up through the ranks of CID and began to have responsibility for crime investigation, I insisted on my staff disclosing to me the identities of their registered informants.
Initially, this caused some resentment, as they were understandably protective of their contacts. However, as all of the local CID intelligence reports passed across my desk, I had to take the broader view, which sometimes gave me an indication of when an informant was starting to abuse his position, perhaps by engaging in further crime and using his relationship with his handler as a form of insurance policy.
In short, I could sometimes see that the tail was starting to wag the dog. In turn, I could warn off the handlers and, in such circumstances, I had no hesitation in coldly sacrificing the informant on the altar of criminal charges as new recruits were continually coming on stream to replace them. Therein lies the secret of running informants: they must be strictly controlled.
It is to my everlasting disappointment that, according to all reports, Special Branch seemed to allow elements of that nest of vipers otherwise known as the Mount Vernon UVF - many of whom are alleged to have been informants - to get away with almost anything, including murder.
With the benefit of hindsight, Special Branch could have cleverly and cunningly used one against the other until they had been totally eliminated and put behind bars.
Instead, if the allegations that they were a protected species are proved to be true, it carries with it an everlasting stigma on the RUC.
There has recently been a sense of hysteria about the seemingly large amounts of money paid to informants by the PSNI, but as the sums paid out to individuals are, from experience, quite derisory, it indicates that they have recruited a large number of them, for which they deserve full credit.
It would be interesting, but almost impossible, to learn how many crimes had been prevented, or solved, by the use of such people.
Gerry Kelly MLA expresses indignation about the police recruiting young and vulnerable people as informants, but I don't recall any falling into that category, as most were experienced and manipulative career terrorists and ordinary criminals with a strong sense of self-preservation.
Intelligence-gathering, which at times seems distasteful, remains the life-blood of the prevention and detection of serious crime and should be encouraged.
It would come as a surprise to most just how many people are alive today thanks to having been warned off about a threat to their lives based on information gained from informants.