TO the journalist and novelist Jack Holland, Ian Phoenix was a hearing-aid salesman whom he had got to know when the Phoenix family had answered an advertisement in the Belfast Telegraph and rented his house in Italy for part of a summer.

But the real Ian Phoenix was an altogether more dangerous and dramatic character. He was a former paratrooper who had risen through the RUC to become one of the force's key commanders in the fight against the IRA: a senior member of the controversial and secretive €4A intelligence unit and head of the RUC's specialist surveillance section. In June, 1994, he was one of 25 top British intelligence officers who died when their helicopter crashed into a hill on the Mull of Kintyre on the way to a high-level security conference in Scotland. Only then did Holland find out who his wine-and travel-loving friend was.

The writer, from a nationalist West Belfast background, has, teamed up with Phoenix's English' wife, Susan, to write a remarkable book, based largely on the dead policeman's personal diaries. Susan is herself clearly an impressive woman, a self-taught psychologist and campaigner for the deaf, who lived for nearly a quarter of a century with the knowledge that every time her husband went to work in the morning he might be dead by nightfall.

The book they have written is both a 28-year-long love story and, the first credible account of the war in Northern Ireland from an RUC man's point of view. And Ian Phoenix's extraordinary career shows that it really was a war: brutal, bloody and extremely dangerous. The first attempt to murder him came in 1973 when he was a sergeant in north Belfast. When Phoenix became an €4A team leader, he stopped his wife cleaning the car. The number plates, in particular, were to be left dirty - "it makes it more difficult for potential murderers to identify us".

Other precautions included writing down the numbers of any cars which passed the house too often; getting the children to lie about what their father did for a living; keeping a gun under the pillow and in Susan's handbag; and dropping a bunch of keys on the ground every time the car was left anywhere in order to check for booby-trap bombs.

Phoenix was involved in a leadership role in many of the key anti-IRA actions of the 1980s and 1990s. In 1983, his men disrupted an IRA attempt to murder a judge in Belfast, by first detonating a milk float at his home and then turning up in a hoax ambulance to finish off the job.

In 1985, he led the team which captured Patrick Magee, later convicted of the Brighton bombing. In 1987, he headed the RUC unit which took part in the Loughgall ambush, in which eight IRA men were killed, the largest number of republicans killed in a British military operation since the War of Independence. Following that spectacular and bloody success, the unflappable Phoenix was unusually upset and reflective. At home in his converted farmhouse on the County Antrim coast he sat in a chair in front of his wife and cried at the waste of life he had witnessed: "Young Irishmen should not be throwing their lives away like that."

In many ways Ian Phoenix was the archetypal British comic-strip hero: a boy from a poor County Tyrone background who rose to become a tough, decisive and humourous anti-terrorist commander; a man who did not suffer fools gladly, especially when they were his superior officers; a lover of good company and fine, wines; broad-minded in politics, and with social conscience enough to risk his career by his involvement with his wife's work for the deaf.

He was also a Rambo-style militarist, who believed that the IRA could be defeated by good intelligence and force of arms, and was suspicious of the compromises forced on the police by the peace moves of the early 1990s. He put forward the crazy notion of a helicopter assault force equipped with heavy machine guns manned by SAS airborne troops which would sweep down on an IRA active service unit "and simply obliterate it".

Phoenix makes compelling reading not only for its insider's account of the RUC's war against the IRA, but also for its insights into the republican movement. It features €4A's list of Belfast's 27 top IRA men, and bluntly states RUC intelligence's belief that as late as 1993 the three most prominent leaders of Sinn Fein were also on the IRA Army Council.

In the wake of the clamour about Neil Jordan's heroic portrayal of Michael Collins, this book is a salutary reminder that the Northern Unionists also have their war heroes and Ian Phoenix is undoubtedly one of them.