While the Sinn Fein leader spoke in a New Year's interview of stepping up the unification campaign by beginning fresh lobbying in the United States and Great Britain, he also spoke of 40-year spans for change.

And MLA Simon Hamilton said it was clear from the remarks, which focused on unity but made no mention of 2016, that the oft-noted target date had been quietly dropped.

He said: "We have become accustomed down through the years to habitual pronouncements from Sinn Fein that their primary aim of achieving a united Ireland was a few short years away from becoming a reality.

"In 2000, Mr Adams himself spoke of how he saw 'no reason why we cannot celebrate the 1916 Rising in the year 2016 in a free and united Ireland'.

"This view was echoed by Martin McGuinness in 2003 when he said: 'Gerry Adams has said 2016 and I think that is achievable'. Now, Gerry Adams is talking about 40-year spans. So much for Sinn Fein's boasts of Irish unity by 2016."

While Mr Adams did not give a start and end date for his 40-year span, he discussed unification in detail and did not mention 2016.

Mr Adams said his party wanted to encourage debate towards ending partition.

"All of this is part of a process," he added.

"I like to judge it – because it's convenient to do so – in a 40-year span.

"And 40 years in a lifetime is huge, but in history it's only a blink.

"If you consider what things were like here (across Ireland) 40 years ago in terms of both the Orange state; the conservative, impoverished state in the south; the fragmented and very minimalist republican development.

"And then you fast-forward to now – without for a moment minimising all the tragedies and difficulties that have occurred in between – you can see how things have moved ahead.

"That's what's going to happen in the up-coming period. It's an incremental process of building the republic day-by-day."

Regardless of just when Mr Adams sees 40 years coming to an end, Mr Hamilton said Sinn Fein had "set aside their smugness and the supposed certainty of a united Ireland by 2016 for an undefined date in the distant future" which appeared to be beyond the lifetimes of the current leadership of republicanism.

"Gerry Adams has effectively admitted that he will never deliver a united Ireland," the MLA maintained.

This pessimism on the part of republicans was in stark contrast to the sense of inevitability about a united Ireland which was felt by many unionists in the past, he said.

"Gone are the days of doom and gloom under the UUP, to be replaced by the strong and confident leadership offered by the DUP," claimed Mr Hamilton.

"Unionists now see the status of Northern Ireland as an integral part of the United Kingdom stronger than ever and republicans robbed of their dreams. The DUP strategy is working. We have turned the tide.