In its profile of Lynn Boylan, the Dublin European election candidate, on the party website, Sinn Féin emphasises the fact that she is a member of its ard comhairle and that she works in Ballymun as a community programme co-ordinator with an environmental NGO. It also points out that she was appointed chairwoman of the Safefood Advisory Board, an all-Ireland body, in 2010.

She holds postgraduate qualifications in environmental impact assessment and in European environmental conservation from University College Dublin.

It does not say, as it happens, that she was the party candidate in the Kerry South constituency in the 2007 general election. In that election, then using the Irish version of her name Lynn Ní Bhaoighealláin, she polled just 1,375 votes. She has no other political experience.

Matt Carthy, the Sinn Féin candidate in the Midlands and North West European constituency has been a member of Monaghan County Council since 2004. He polled 1,302 votes and took the second seat in Carrickmacross in the 2009 local elections.

The party’s profile of Liadh Ní Riada, its candidate in the South constituency, gives the name of her Sinn Féin Cumann in Cork, tells us that she has been a member of the Sinn Féin ard comhairle since 2013, that she worked previously as a television producer and director and that she is the youngest daughter of the musician Seán Ó Riada. She has never contested an election before.

Sinn Féin has deployed a very astute candidate strategy for this European election. All of their candidates in the Republic are newcomers to large-scale political contests.

They are relative unknowns: none of them had much profile outside of their sector or county. They represent the fresh, younger face of Sinn Féin. They carry none of the baggage of the party’s past support for the IRA campaign.

They may each prove to be substantial and able parliamentarians; we can’t really know that until they are tested in public office, but it is clear they are each very able candidates.

Party brand
Sinn Féin wisely decided to major on the party brand rather than the candidate factor for this European election. Five years ago, Sinn Féin got 11 per of the first preference vote.

The party is now running at almost twice that figure in polls.

Since the last local and European elections, Sinn Féin in the Republic has successfully moved from being a niche left-of-centre party of protest towards becoming the broader catch all-party it is in Northern Ireland.

The shift has arisen primarily from the political volatility caused by the current economic crisis.

Sinn Féin has also grown because it has proven to be an able and effective party of opposition. That is due primarily to the parliamentary and media performance of Mary Lou McDonald, who has already become the de facto leader of Sinn Féin in the Republic.

She has more impact in the Dáil chamber than Gerry Adams and supplements that with her strong performances at Oireachtas committees.

Many voters, and not just women, have admired her capability and her tenacity in standing up to men 20 years her elder at Leaders' Questions. Her Late Late Show appearance some weeks ago was a significant factor in the party's most recent bounce.

This growing public popularity is why McDonald has been placed front and centre in all key media opportunities in these elections.

It is too early to know what impact this week’s arrest of Adams will have on Sinn Féin’s carefully crafted strategy for these elections.

Impact of the arrest
At the time of writing, Adams is still in custody. If Adams is released without charge, and with charges unlikely to be directed later, then the party may be able to move on promptly from the impact of the arrest.

If, however, this weekend or on some later date, Adams is charged, then the political implications could be massive. It could undermine his continued leadership of Sinn Féin, it would stall the party effort to increase its support in the Republic and it could even cause a significant wobble in the peace process.

One has to believe that Sinn Féin’s core voters in the Republic will be unmoved by Adams’s arrest.

Sinn Féin’s outdated language about “dark sides” in policing out to get their leader is aimed at those core voters here and in Northern Ireland.

The impact on the newer Sinn Féin voters is more difficult to determine.

While their move to Sinn Féin is shaped by economic and social concerns, it seems likely that if this controversy about Adams and the Jean McConville case continues, these newer vote will become less enthusiastic.

One thing that is already clear is that the Mary Lou momentum has already been stalled.

1980s rhetoric
Since Wednesday night, McDonald has had to go on media and use 1980s rhetoric about how the arrest of her party president was politically motivated. She was also required to say again and again that she believes Adams was never in the IRA.

Each time she parrots this incredible line from Adams, another piece of the credibility and standing which she has acquired cross-examining overpaid charity executives and challenging incommunicative bankers seeps away.