She was pleasant enough, but always businesslike. No small talk. She would smile and nod in acknowledgement as we climbed aboard the helicopter before pulling on a headset to drown out the noise as the big Wessex rose into the darkness above RAF Aldergrove, 15 miles north of Belfast.
Her arrival from London, usually the day before Christmas Eve, was always unannounced. In the aftermath of the 1981 hunger strike republicans wanted her dead, and paranoid loyalists claimed the right to distrust her when she signed off the 1985 Anglo-Irish Agreement, which they claimed weakened the constitutional link with the rest of the UK.
But the hostility and the threat to her life never seemed to faze her as we crossed the South Armagh countryside, or headed west to touch down at some military outpost close to the border with the Irish Republic where the IRA frequently engaged the enemy in lengthy and ferocious gun battles.
A small team travelled with her. In later years it was headed up by her private secretary, Charles Powell. There was her press secretary, Bernard Ingham, a gruff Yorkshireman, and there would be Northern Ireland's secretary of state at the time.
Also with her would be a Downing Street typist hammering away on the keys of a portable typewriter balanced on her knee, two plain-clothes Metropolitan Police detectives, and a soldier who rarely left her side.
The latter was small with sharp features and dressed in combat gear with a red beret pulled to one side and the badge of the Parachute Regiment on each shoulder. He carried a gun in a holster, but never spoke - not even to exchange seasonal greetings.
Mrs Thatcher just sat there, back to back, her eyes closed, cat-napping without a worry in the world. Or so it seemed - just feet from where another soldier positioned himself at an open door, his finger on the trigger of a belt-fed general purpose machine-gun on a tripod with the barrel pointed downwards.
A second helicopter with a full compliment of passengers followed behind, and then were was a third some distance away.
It was referred to as a "decoy". But there was never an explanation as to its precise role.
A seat was always reserved for a representative from the Press Association on the VIP helicopter and every year without fail I drew the short straw.
It was always a hairy ride. We once flew to Enniskillen, Co Fermanagh, skimming the treetops of the Clogher Valley because of the fear of being hit by one of the surface-to-air missiles which the IRA had smuggled in from Libya. It was just a few days before she resigned.
Mr Ingham disembarked, clearly relieved the party had landed safely. He called me aside and remarked just loud enough for his boss to hear: "That's the first time I've ever flown underground... Even the cows ducked."
There was a trip before that to Forkhill, South Armagh. The helicopter swayed from side to side on our approach before dropping like a stone into a heavily fortified military base where we had to run, heads down, to a bomb-proof shelter for fear of missiles being fired over the high perimeter fence. Here was the prime minister and her entourage sprinting for cover.
Afterwards her obedient husband, Denis, complained when he discovered oil stains on his tweed jacket. Nobody was sure how they got there.
The dictatorial and quick-tempered Sir John Hermon, the chief constable at the time, was terrified she would be harmed on his watch, especially after the October 1984 bombing of Brighton's Grand Hotel.
The day following that attack on the prime minister and delegates at the Conservative Party conference, I was summoned to west Belfast to take delivery of the statement confirming the IRA's involvement which included the words: "Remember we have to be lucky just once."
The man who handed me the folded note - it was typed on pinkish coloured paper - is still walking the streets. We meet from time to time, occasionally over coffee, but that secret encounter just off the Falls Road all those years ago remains just that.
Curiously, neither Downing Street nor the police ever discussed it with me either.
Mrs Thatcher always had a handbag on her arm as she strode out ahead of everybody else. She could be thoughtful and charming when visiting wounded soldiers at Musgrave Park Hospital, Belfast, or comforting and respectful while commiserating with widows and families of murdered police officers in a side room at RUC headquarters in Belfast.
She was visibly upset when she attended a church service in the aftermath of the IRA's Remembrance Day bombing in Enniskillen in November 1987.
She had to be pulled away from grieving relatives because a flight was waiting to take her on to Paris for a meeting with French president Jacques Chirac in the Elysee Palace that night.
Apart from the day she left Downing Street for good, it was the only time I witnessed her show emotion.
Everyone, particularly military commanders, seemed to be in awe of the Iron Lady.
She called to be briefed, sometimes wearing a beret belonging to whichever regiment was hosting the visit.
But how the IRA despised her. She was a figure of hate, blamed for allowing 10 republicans to die on hunger strike at the Maze Prison in 1981.
Sir John Hermon was fascinated by her. They respected each other. She stood by him through some difficult times, especially when he was under serious pressure over claims that his men were involved in a state sanctioned so-called shoot to kill policy against the IRA which may have extended far beyond the shores of Belfast Lough.
Was the murder of two RUC detectives shot dead by the Provisionals inside the Liverpool Bar in the city's docklands in August 1987 what prompted a chain of events which ended with SAS soldiers killing three IRA volunteers planning to detonate a car bomb in Gibraltar the following year?
Was the surveillance operation against the Gibraltar trio directed from Whitehall?
What did Mrs Thatcher and the Chief Constable in Belfast really know about that particular security operation, which haunted the IRA for years?
A demanding media in Belfast frequently challenged her grasp of Northern Ireland's political complexities. which sometimes tended to baffle and bewilder other visiting British ministers.
But not her. She had the measure of all of us, even the aggressive Eamonn Mallie, who famously confronted her with his microphone early one afternoon at a room overlooking the gardens at Stormont Castle.
Not so much an interview, more a vicious exchange, and her dislike of Downtown Radio's then political editor was obvious.
She could be equally dismissive of those who were supposed to be on her side. It was Christmas 1982, just before she was due to fly back to London after making a live televised teatime address to an audience in despair at a growing political and security crisis.
Jim Prior was secretary of state at the time and keen to get her public backing for a new political initiative, inviting nationalists and unionists to sit down together at Parliament Buildings.
But she either forgot, or deliberately failed to mention his plans - he called it a Constitutional Convention - leaving Mr Prior incandescent.
It was getting late after another long and tense day.
Some of the Downing Street staff were beginning to show signs of weariness and I had a wife and two young sons waiting patiently at home getting ready for Santa's arrival.
The prime minister liked a stiff Scotch at the end of every Northern Ireland visit but before she could raise the tumbler she was handed after emerging from a makeshift TV studio in an adjoining room at Aldergrove, Mr Prior let rip.
His face was a puce. "How could you?" he thundered.
"How could you? How could you go through with that and not talk about the Convention? I can't believe you did that..."
She fired him a withering look of such intensity no-one who was there that night dared respond - not even her husband, who eventually broke the silence to inquire if she had enough soda water in her Bell's whisky.
"Yes, Denis," she replied. "I'll just take another dash if you don't mind, a small dash will do."
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