Gerry Adams resigned his seat from the British House of Commons on 26 January 2011, and in accordance with the rules and customs of Westminster was granted the position of Crown Steward and Bailiff of the Manor of Northstead in order to facilitate this. This was wrongly reported as a barony by David Cameron; a baron is a member of the British nobility, while a steward and bailiff is more akin to a groundskeeper. Adams is no longer the bailiff, as the position was granted in April to Labour MP Peter Soulsby.
In any case, a point made on Twitter by mgconnor (of iCampaigned) was that Michelle Gildernew, should she be interested in standing for the Irish presidency, as is speculated, would similarly be expected to resign her seat. It was easy for Adams, as it was a near certainty both that he would succeed Arthur Morgan in Louth (he topped the poll) and that Sinn Féin would win the Belfast West bye-election (Paul Maskey won with 70%).
Neither would be true in the case of Gildernew, who is quite unlikely to win, while she won the Fermanagh–South Tyrone seat for Sinn Féin in 2010 by only 4 votes. Will anyone ask whether she should resign as Adams did, or would she respond that it’s equivalent to Gay Mitchell continuing as an MEP while standing? While that could be fair, it won’t always be as easy for Sinn Féin to transfer representatives across the border as between West Belfast and Louth.
A more pressing issue is how any Sinn Féin candidate would be nominated. With 14 TDs and 3 Senators, they are three short of the 20 Oireachtas members which would nominate a candidate. They could appeal to certain members of Fianna Fáil, particularly as they are not running a candidate, and that there are Fianna Fáil senators who owe their seats to Sinn Féin voters. I’m not sure what the relations are now between their former party colleague, Independent TD Thomas Pringle, but he would be a possibility.
Even at the 10% Sinn Féin achieved at the general election in February, it would be 10% more than Fianna Fáil will receive in this election. Add to that Socialist and People Before Profit voters who would be glad of a left-wing anti-bailout candidate, and they would probably reach around 15% at a first reasonable estimate.