SDLP high-flyer Conall McDevitt has said he will not be returning to public life after dramatically resigning from the Assembly following revelations that he failed to declare payments from a former employer three years ago.
The South Belfast MLA – tipped as a potential future leader of the party – had been under mounting pressure in recent days over his use of official allowances.
This afternoon, Mr McDevitt tweeted: "Thanks everyone for your kind words and messages. Just want to make clear that I will not be returning to public life in the future."
The former public relations expert, who had been due to represent the party at the forthcoming negotiations on flags, parades and dealing with the past to be chaired by the American diplomat Richard Haass, admitted he had fallen below expected standards, and apologised "unreservedly".
Mr McDevitt insisted he had done nothing wrong in using Assembly office cost allowances to pay four researchers through his wife's consultancy company.
He also defended using his £16,000 Policing Board allowance to pay his wife, Dr Joanne Murphy, for research work on policing over the last two years.
Yesterday he confessed: "Between March 2010 and August 2010 I received a total of £6,750 from my former employers, Weber Shandwick.
"These payments related to internal work within Weber Shandwick."
The MLA, who stood for the SDLP leadership just over two years ago, was formerly managing director of the Belfast office of public relations firm Weber Shandwick, a post from which he resigned in December 2009.
His statement yesterday went on: "I provided support and mentoring to the new management team following my departure from the company.
"I was never asked to nor did I ever represent any of the company's clients whilst an MLA."
He had not included the payment in the Assembly Register of Members' Interests which he had previously altered to cover the payments from his office cost allowances.
He then also admitted: "These payments were made through JM Consulting, a consultancy which my wife has an interest in.
"These are registerable interests under the Assembly rules. I have now registered these earnings on my register.
"My failure to register these interests at the time means that I have fallen below the standards expected of me in public office.
"I have done my best to discharge my duties as an MLA with integrity but there is no question that I failed to do so on this occasion.
"I apologise unreservedly for my failures in this regard."
He is the first senior Northern Ireland politician to resign from his party since veteran Ulster Unionist Lord Maginnis quit over remarks comparing homosexuality to bestiality.
His resignation will mean an SDLP co-option to fill his seat, possibly as early as next month.
After his official statement, Mr McDevitt added last night: "I entered politics to try and bring about change and positive change... therefore I think there's a duty on me to resign my position in public life in order to protect the integrity of the institution and to acknowledge the error that I have made."
Accepting his resignation, Alasdair McDonnell, who defeated Mr McDevitt to replace Margaret Ritchie as leader of the beleaguered party two years ago, said McDevitt had done the right thing "after admitting his failure to register funds received by him during his time as MLA in accordance with Assembly rules".
"As elected representatives we quite rightly hold ourselves and are held by the electorate to a very high standard," the leader added.
"South Belfast was very well represented by Conall McDevitt and he made a very positive contribution, not only to the constituency but also to the wider SDLP, where he showed energy, enthusiasm and drive.
"Conall will be a loss to the Assembly party and to South Belfast and I would like to wish him and his family all the best for the future."
In his statement, Mr McDevitt added: "It has been the greatest honour of my professional life to serve the people of South Belfast and the SDLP since January 2010.
"I will forever treasure the opportunity given to me to make a contribution to the building of a new society here. That work will be continued by my successor whomever he or she may be.
"I would like to ask for some privacy at this time for myself and my family."