U-turn by Adams shows a man rattled by Mairia's claims

But one of the few exceptions to this rule is Sinn Fein. While he was out in his constituency yesterday, Mr Kenny was asked to comment on the latest imbroglio over allegations made by Mairia Cahill that she was raped by a member of the IRA in 1997 and subsequently interrogated about her accusations. And his response was robust, to say the least.

"I think there's been a despicable, utterly despicable conduct by Sinn Fein to discredit Mairia Cahill over the last period," he said emphatically, adding that he thought her to be "articulate, to be courageous and to be a person of great confidence, and I'm looking forward to meeting her".

And no doubt he is looking forward to sitting down with the grand-niece of the late republican icon Joe Cahill. The timing of her explosive revelations in BBC's 'Spotlight' documentary last week must seem serendipitous to the Taoiseach right now.

This is because the Government - instead of basking in what should be a period of relative stability in the aftermath of what (so far) appears to be a landmine-free Budget as the economy improves apace - is struggling to deal with growing public anger over the introduction of water charges by the beleaguered Irish Water company.

Then there is the inexorable rise of Sinn Fein. A poll released earlier this month put Fine Gael and Sinn Fein neck-and-neck in popular support for the first time, with both parties level at 24pc (no change for Fine Gael, and a four-point rise for Sinn Fein).

Even more gallingly for Mr Kenny, his own popularity rating is 26pc, while Gerry Adams' popularity had increased by two points to 35pc.

And this increase occurred despite the Sinn Fein President being embroiled in other controversies - most recently when he was questioned for four days last May by the PSNI in relation to the 1972 IRA murder of Belfast mother-of-ten Jean McConville. (He was released without charge and a file was sent to the North's Public Prosecution Service to decide whether further action should be taken.)

Yet - despite the blizzard of international and domestic publicity generated by his arrest and questioning, which added to widespread scepticism over Mr Adams' repeated denials that he was ever a member of the IRA - the popularity of the Sinn Fein leader remains undiminished.

And recently, both Mr Adams and Fianna Fail's Micheal Martin have been battering the Taoiseach in the Dail over the ongoing shambles that is Irish Water. When Mr Adams isn't around his deputy leader, Mary Lou McDonald, puts the boot even more ably into Mr Kenny.

But the allegations of Mairia Cahill appear to have rattled Sinn Fein. Mr Adams posted an unprecedented U-turn blog on Sunday evening in which he conceded the IRA had investigated allegations of sexual abuse and assault, while his ultra-loyal deputy once again finds herself walking the precarious political tightrope of condemning former actions of the IRA while simultaneously standing resolutely by her party leader.

So the Taoiseach must be tempted by the sight of the open goal yawning in front of him, with a meeting this week with Ms Cahill offering a golden opportunity to score some points against Sinn Fein.

However, it could very easily turn into a hospital pass - and the Taoiseach could find himself charged with using a vulnerable woman as a political football.

Observers of the frequent clashes between Enda Kenny and Gerry Adams during Leaders' Questions in the Dail can only conclude that the Taoiseach's antipathy for Sinn Fein is a visceral reaction.

His affable public persona can't hide his contempt for the party, and he frequently detours from the business in hand to take cuts off the Sinn Fein leader - for instance last year he told Mr Adams during one tense exchange: "I would love to hear you speak the truth about some elements of your past. You might someday tell the truth about the tragedy and the remorse and about the compassion that should have been shown for Jean McConville."

One political advisor believes the Taoiseach needs to tread carefully.

"Enda will have no truck with the Shinners. And given his genuine ability to empathise with people in this sort of sit-down meeting, he's not likely to dial down his response afterwards. It's tricky - if he's too muted, he'll be seen as uncaring, but if he's too harsh he could be perceived as making political hay about a sensitive matter," he said.

Already, Sinn Fein is protesting that the Taoiseach is playing the man and not the ball, with Mr Adams last night condemning Mr Kenny's comments about Sinn Fein and Mairia Cahill as "mischievous and politically motivated".

Moreover, the Taoiseach should heed the fact that there is a perception that justice is not always swiftly executed by this government when it comes to women in distress. While his official apology to the Magdalen women in 2013 was eloquent and whole-hearted, it came only after widespread criticism that the government was foot-dragging over the issue. Also, the Government was only finally spurred into action to deal with the 20-year-old X Case judgment after public outrage over the tragic death of Savita Halappanavar.

As the Taoiseach has found to his cost during recent controversies, it doesn't take much for an open goal to turn into an own-goal.