Not one of them is what you would describe as an easy character, and they have often had turbulent relations with one another.

There have been other gifted unionists – I am too young to remember Desmond Boal’s political career and you don’t get a first in law from Cambridge, as Nigel Dodds did, without being of a very high rank of intelligence.

But those five men were both highly smart and highly theatrical – although none of them was putting on an act.

Few people in Northern Ireland have had the impact that Ian Paisley did, but Mr Robinson almost did, in his own way.

One of the most telling aspects of the first minister’s career is how he handled the controversy surrounding his wife, Iris.

Most men would have collapsed under the pressure and publicity of it all.

I wrote with confidence in an analysis piece in early 2010 that Mr Robinson “has now been so battered by events that it seems unlikely he will wield the influence that he did”.

When he lost his Westminster seat months later, that assessment seemed to be vindicated.

Wrong. He entered the zenith of his power and influence.

In one respect, we should not be surprised, given his long-term patience and determination.

My first sense of Mr Robinson was when I was a child, always seeing him on TV at Dr Paisley’s side. I recall him as a ballboy in a Rowel Friers cartoon in which Paisley was a player on the tennis court.

The impression then was of a man who was always present, but not so important. In fact, he gradually became hugely important.

As a student in the early 1990s I recall sitting in the gallery of the House of Commons and seeing him speak in the chamber without notes. Barely over 40, he was fluent and impressive.

Adroitly, he always appeared hardline but when you examined his speech he often wasn’t.

In 2010, reporting newly released Stormont papers, I came across minutes of the 1980 Atkins talks at which Mr Allister, Dr Paisley and Mr Robinson were present. They sang from the same hymn sheet but Mr Robinson gave off a more flexible air.

The other two seemed more often to be in uncompromising agreement.

At the 2005 election counts I recall asking Mr Robinson about IRA decommissioning and he answered cautiously, to a reporter, in effect speaking hypothetically about what they might do now.

It soon became evident that he had been able to see clearly that the IRA would now move more fully to disposing of its arms, as indeed within weeks it promised to do.

He was a far-sighted politician, and much more subtle than he seemed.

Another encounter with Peter Robinson that comes to mind was when I saw him after midnight one early morning in Cluan Place in the summer of 2002. For some reason, republicans decided to whip up tensions at that east Belfast interface back then.

When the violence became a crisis, Mr Robinson signed and helped shape a statement by a range of unionists and Protestant churchmen.

As the wording was finalised, he suggested mentioning the INLA element in the Short Strand, and seemed to want to introduce some nuance to the statement.

His Achilles heel was his thin skin and prickliness. This was painfully apparent in the 2010 BBC interview with Seamus McKee, in which he let himself down badly in response to reasonable questions about a land deal.

Which brings me to the respect in which it is in fact surprising that he weathered ‘Irisgate’ at all.

Some preternaturally calm men such as David Cameron seem to be able to stay unruffled despite being hammered by perpetual external crises and relentless personal abuse.

Mr Robinson latterly seemed decreasingly able to do that, and his sensitivity appeared even ultimately to affect his judgment. Meanwhile, his health was suffering.

A more consistently charming (because he can be very charming) and thick skinned Peter Robinson might have sailed on at the top of politics into his 70s, as he evidently had the energy to do.

• Ben Lowry is News Letter deputy editor