Harris and McGuinness are poles apart politically and probably wouldn't relish being mentioned in the same sentence.

Harris, the Cork-born commentator and former spin-doctor for several political parties, strongly opposes Sinn Fein.

During the Republic's presidential election, he branded it a "national socialist movement" like the Nazis and condemned the southern media for not concentrating enough fire on McGuinness's IRA past.

"Good authority" is a term Harris developed though the image of children fighting with their neighbours. Good Authority consisted in calling your own in instead of backing them up, or making excuses for them, or - worse still - joining in.

It was the most effective way to stop disputes spinning out of control and it invited reciprocal gestures from the other side.

Niall O Donnghaile, Belfast's Lord Mayor, caused an embarrassing scene at the Duke of Edinburgh awards ceremony by stopping halfway through distributing the awards. He retreated to his parlour, leaving Gordon Topping of the awards scheme to complete the job.

After an unexplained 45-minute delay, it emerged that the mayor had thrown a hissy fit when he discovered that one of the honourees, a 15-year-old girl, was a member of the Army Cadet Force.

It was appallingly rude - as well as politically inept. O Donnghaile's apology was undermined by the fact that he avoided giving an undertaking not to do the same thing again.

Any spin-doctor would have advised him that you don't measure apologies with a micrometer. If you can't say all that is needed, it is better to keep silent.

O Donnghaile floundered and unionists made the most of it, voting not to accept his apology - though the council, as a whole, opted to accept it.

Angry crowds gathered at the City Hall, demanding the Lord Mayor's resignation and accusing the DUP of a "sell out".

In response, Ruth Patterson, the deputy Lord Mayor, suggested that, if more people voted DUP, then this situation wouldn't arise - a hint that they could then overturn the power-sharing arrangement on the council.

The situation became increasingly ugly and no one seemed willing to intervene. Sinn Fein councillors tried to create a diversion by proposing a 'Nollaig Shona' sign ('Happy Christmas' in Irish) at the City Hall in reciprocation for the mayor's rejected apology.

It was like Harris's fight in the street and McGuinness showed himself to be the only grown-up ready to intervene.

On Tuesday, in the Assembly, he took charge, metaphorically calling O Donnghaile in from the street. He explained that young Niall was sorry for his behaviour and had made "a very clear commitment that that will not be repeated".

"The important thing to do, whenever someone makes a mistake, is to put your hand up and to apologise," said McGuinness, urging everyone "not to make a meal of it" and move on.

It is the sort of advice we were given at primary school, but some of us seem to have forgotten the lesson.