There are any number of books, mostly autobiographical, from ex-members of the security forces, most of which have more style than substance, Andy McNabb for instance.

'Undercover Cop' by Paddy Craig, a pseudonym, is definitely one of the better ones. It has loads of hair-raising material relating to infiltrating dangerous criminal gangs, both here, the UK and in Europe posing as a Loyalist paramilitary and, as well, it has a fascinating insight into the obstacles he came up against from within the RUC/PSNI.

His number one adversary, readers won't be surprised to hear, was the Special Branch, given the fact his unit and the Special Branch were dealing with the same sensitive material, and the same contacts whom the Branch jealously guarded.

Then, there were the background jealousies from supposed colleagues at the unprecedented success of the surveillance unit he single-handedly at Castlereagh in mid-1997.

Its services were constantly utilised by Police forces in the UK, colleagues he admired and who appreciated his worth.

And, he was a cop with a difference. Having passed out from Enniskillen RUC Training Depot in 1975, he cut his rookie's teeth in Roden Street before getting his first taste of CID work in Belfast's Hastings Street Station.

In those days, access to specialist training was well night impenetrable to RUC officers, but Craig was something of a frontiersman and found a way. Having set up his undercover surveillance unit at Castlereagh, he set about acquiring those specialism which he later passed on to his own officers.

One area of weakness he quickly identified was a complete lack of know how in a situation where an undercover cop's car is hemmed in by baddies. Aware that the West Midlands Police Traffic Branch were the recognised experts in the field (they trained the SAS in specialist driving skills), he scrounged the money to pay for lessons.

"Soon', he records, "we could reverse at 70 mph, pull the car through 180 degrees and head off in the opposite direction without losing a second, making escape from an ambush scenario a real possibility."

The book is littered with James Bond-type stings, which, in the main, worked. Posing as a haulier seeking to make extra cash from exporting drugs across Europe, he breached the upper reaches of a notorious criminal gang to help pull off a five million euro cannabis haul in 1998.

In another sting, he managed to intercept a 20m euro drugs consignment after infiltrating a Kurdish terror group.

There were too the narrow escapes when his cover was almost blown or about to be blown, getting a tip-off just in time after one jealous member of the Gardai had leaked vital information to a Dublin-based gang.

And, there when the time when, having presented himself as that Loyalist terrorist with the Catholic forename, Paddy Craig at the palatial home of a counterfeit money king, he was handed a towel and flip-flops so he could trade by the pool side. Unknown to all and sundry, he was carrying his stock in trade, a hidden tape recorder in his backpack.

The author's white knuckle description of his dilemma is worth the price of the book alone: 'My stomach was a complete knot. All I could think about was a Bond movie in which the hero arranges to meet one of his enemies in a sauna. Real life isn't like the movies, however.

They never tell you about things like this in training."

But, having survived 30 years in the Police, Craig certainly had enough survival tricks up his sleeve, things such as making sure his shoes were always shiny, never sitting at a bar (always stand) and taking up position near the door so he could survey anyone who came in.

It is ironic that, having put his body on the line for Queen and country, he was influenced to call it a day, not by criminals (although the increasing use of guns was a factor: he never carried a gun himself, relying on back-up support when summoned) but by the lack of psychological support following a traumatic incident, those petty personal jealousies from colleagues ('I was treated as a virtual pariah') and the low-life reputation which an undercover had.

But, at least he retired (as Deputy Head of Police Intelligence) with his integrity intact, albeit regretful that the contribution that he and others like him who had paid the ultimate price had gone unappreciated.

'Undercover Cop' by Paddy Craig was released last Friday. It is available in paperback and published by Gill & Macmillan at £11.99.